fix: customParseFormat support parsing X x timestamp
fix #1533
**Describe the bug**

When `x` and `X` from [dayjs/plugin/advancedFormat](https://day.js.org/docs/en/plugin/advanced-format) is used with strict mode parse fails:
```js
dayjs(`/Date(${dayjs().format('x')})/`,"/[Date](x)/").format('/[Date](x)/')
> "/Date(1623787200000)/"
dayjs(`/Date(${dayjs().format('X')})/`,"/[Date](X)/").format('/[Date](X)/')
> "/Date(1623787200)/"

dayjs(`/Date(${dayjs().format('x')})/`,"/[Date](x)/",true).format('/[Date](x)/')
> "Invalid Date"
dayjs(`/Date(${dayjs().format('X')})/`,"/[Date](X)/",true).format('/[Date](X)/')
> "Invalid Date"
```
**Expected behavior**
last 2 examples should parse correctly as fist 2 cases do.

**Information**
tested on recent version of chrome (in dev tools of https://day.js.org/)

looks like related to:
https://github.com/iamkun/dayjs/pull/1467
https://github.com/iamkun/dayjs/issues/929
https://github.com/iamkun/dayjs/pull/1467
Parsing with Unix Timestamp tokens X/x and strict mode results in Invalid Date
diff --git a/src/plugin/customParseFormat/index.js b/src/plugin/customParseFormat/index.js
index 536a6654c..73e48eb91 100644
--- a/src/plugin/customParseFormat/index.js
+++ b/src/plugin/customParseFormat/index.js
@@ -175,6 +175,7 @@ function makeParser(format) {
 
 const parseFormattedInput = (input, format, utc) => {
   try {
+    if (['x', 'X'].indexOf(format) > -1) return new Date((format === 'X' ? 1000 : 1) * input)
     const parser = makeParser(format)
     const {
       year, month, day, hours, minutes, seconds, milliseconds, zone

diff --git a/test/plugin/customParseFormat.test.js b/test/plugin/customParseFormat.test.js
index 65a702997..97fe8fb73 100644
--- a/test/plugin/customParseFormat.test.js
+++ b/test/plugin/customParseFormat.test.js
@@ -368,3 +368,12 @@ it('custom two-digit year parse function', () => {
   const input3 = '99-05-02'
   expect(dayjs(input3, format).year()).toBe(1899)
 })
+
+it('parse X x', () => {
+  const input = '1410715640.579'
+  const format = 'X'
+  expect(dayjs(input, format).valueOf()).toBe(moment(input, format).valueOf())
+  const input2 = '1410715640579'
+  const format2 = 'x'
+  expect(dayjs(input2, format2).valueOf()).toBe(moment(input2, format2).valueOf())
+})

{"test/plugin/customParseFormat.test.js": {"run": "PASS", "test": "FAIL", "fix": "PASS"}}
{"test/timezone.test.js:Add Time days (DST)": {"run": "PASS", "test": "PASS", "fix": "PASS"}, "test/plugin.test.js": {"run": "PASS", "test": "PASS", "fix": "PASS"}, "test/locale/de.test.js": {"run": "PASS", "test": "PASS", "fix": "PASS"}, "test/locale/sk.test.js": {"run": "PASS", "test": "PASS", "fix": "PASS"}, "test/plugin/advancedFormat.test.js": {"run": "PASS", "test": "PASS", "fix": "PASS"}, "test/plugin/weekYear.test.js": {"run": "PASS", "test": "PASS", "fix": "PASS"}, "test/timezone.test.js": {"run": "PASS", "test": "PASS", "fix": "PASS"}, "test/plugin/isSameOrBefore.test.js": {"run": "PASS", "test": "PASS", "fix": "PASS"}, "test/plugin/pluralGetSet.test.js": {"run": "PASS", "test": "PASS", "fix": "PASS"}, "test/timezone.test.js:Diff (DST)": {"run": "PASS", "test": "PASS", "fix": "PASS"}, "test/locale/keys.test.js": {"run": "PASS", "test": "PASS", "fix": "PASS"}, "test/utils.test.js": {"run": "PASS", "test": "PASS", "fix": "PASS"}, "test/plugin/relativeTime.test.js": {"run": "PASS", "test": "PASS", "fix": "PASS"}, "test/parse.test.js": {"run": "PASS", "test": "PASS", "fix": "PASS"}, "test/plugin/localizedFormat.test.js": {"run": "PASS", "test": "PASS", "fix": "PASS"}, "test/plugin/updateLocale.test.js": {"run": "PASS", "test": "PASS", "fix": "PASS"}, "test/constructor.test.js": {"run": "PASS", "test": "PASS", "fix": "PASS"}, "test/plugin/weekday.test.js": {"run": "PASS", "test": "PASS", "fix": "PASS"}, "test/plugin/isLeapYear.test.js": {"run": "PASS", "test": "PASS", "fix": "PASS"}, "test/query.test.js": {"run": "PASS", "test": "PASS", "fix": "PASS"}, "test/plugin/localeData.test.js": {"run": "PASS", "test": "PASS", "fix": "PASS"}, "test/timezone.test.js:UTC diff in DST": {"run": "PASS", "test": "PASS", "fix": "PASS"}, "test/locale/zh.test.js": {"run": "PASS", "test": "PASS", "fix": "PASS"}, "test/locale/ja.test.js": {"run": "PASS", "test": "PASS", "fix": "PASS"}, "test/plugin/declarations.test.js": {"run": "PASS", "test": "PASS", "fix": "PASS"}, "test/plugin/timezone.test.js": {"run": "PASS", "test": "PASS", "fix": "PASS"}, "test/locale/ru.test.js": {"run": "PASS", "test": "PASS", "fix": "PASS"}, "test/locale/bn.test.js": {"run": "PASS", "test": "PASS", "fix": "PASS"}, "test/plugin/dayOfYear.test.js": {"run": "PASS", "test": "PASS", "fix": "PASS"}, "test/timezone.test.js:UTC add day in DST": {"run": "PASS", "test": "PASS", "fix": "PASS"}, "test/manipulate.test.js": {"run": "PASS", "test": "PASS", "fix": "PASS"}, "test/locale/cs.test.js": {"run": "PASS", "test": "PASS", "fix": "PASS"}, "test/locale/en.test.js": {"run": "PASS", "test": "PASS", "fix": "PASS"}, "test/get-set.test.js": {"run": "PASS", "test": "PASS", "fix": "PASS"}, "test/locale/he.test.js": {"run": "PASS", "test": "PASS", "fix": "PASS"}, "test/plugin/utc.test.js": {"run": "PASS", "test": "PASS", "fix": "PASS"}, "test/plugin/quarterOfYear.test.js": {"run": "PASS", "test": "PASS", "fix": "PASS"}, "test/plugin/objectSupport.test.js": {"run": "PASS", "test": "PASS", "fix": "PASS"}, "test/locale/fi.test.js": {"run": "PASS", "test": "PASS", "fix": "PASS"}, "test/locale/sv.test.js": {"run": "PASS", "test": "PASS", "fix": "PASS"}, "test/plugin/toArray.test.js": {"run": "PASS", "test": "PASS", "fix": "PASS"}, "test/timezone.test.js:Utc Offset": {"run": "PASS", "test": "PASS", "fix": "PASS"}, "test/locale/bg.test.js": {"run": "PASS", "test": "PASS", "fix": "PASS"}, "test/plugin/utc-utcOffset.test.js": {"run": "PASS", "test": "PASS", "fix": "PASS"}, "test/locale/sr-cyrl.test.js": {"run": "PASS", "test": "PASS", "fix": "PASS"}, "test/locale/br.test.js": {"run": "PASS", "test": "PASS", "fix": "PASS"}, "test/plugin/isMoment.test.js": {"run": "PASS", "test": "PASS", "fix": "PASS"}, "test/plugin/isYesterday.test.js": {"run": "PASS", "test": "PASS", "fix": "PASS"}, "test/locale/pl.test.js": {"run": "PASS", "test": "PASS", "fix": "PASS"}, "test/plugin/toObject.test.js": {"run": "PASS", "test": "PASS", "fix": "PASS"}, "test/locale/sr.test.js": {"run": "PASS", "test": "PASS", "fix": "PASS"}, "test/plugin/preParsePostFormat.test.js": {"run": "PASS", "test": "PASS", "fix": "PASS"}, "test/plugin/isSameOrAfter.test.js": {"run": "PASS", "test": "PASS", "fix": "PASS"}, "test/plugin/weekOfYear.test.js": {"run": "PASS", "test": "PASS", "fix": "PASS"}, "test/comparison.test.js": {"run": "PASS", "test": "PASS", "fix": "PASS"}, "test/plugin/calendar.test.js": {"run": "PASS", "test": "PASS", "fix": "PASS"}, "test/plugin/isTomorrow.test.js": {"run": "PASS", "test": "PASS", "fix": "PASS"}, "test/locale/et.test.js": {"run": "PASS", "test": "PASS", "fix": "PASS"}, "test/locale/hu.test.js": {"run": "PASS", "test": "PASS", "fix": "PASS"}, "test/timezone.test.js:UTC and utcOffset": {"run": "PASS", "test": "PASS", "fix": "PASS"}, "test/plugin/arraySupport.test.js": {"run": "PASS", "test": "PASS", "fix": "PASS"}, "test/plugin/isToday.test.js": {"run": "PASS", "test": "PASS", "fix": "PASS"}, "test/locale/hr.test.js": {"run": "PASS", "test": "PASS", "fix": "PASS"}, "test/locale.test.js": {"run": "PASS", "test": "PASS", "fix": "PASS"}, "test/plugin/badMutable.test.js": {"run": "PASS", "test": "PASS", "fix": "PASS"}, "test/locale/sv-fi.test.js": {"run": "PASS", "test": "PASS", "fix": "PASS"}, "test/plugin/duration.test.js": {"run": "PASS", "test": "PASS", "fix": "PASS"}, "test/plugin/isoWeek.test.js": {"run": "PASS", "test": "PASS", "fix": "PASS"}, "test/plugin/minMax.test.js": {"run": "PASS", "test": "PASS", "fix": "PASS"}, "test/plugin/isoWeeksInYear.test.js": {"run": "PASS", "test": "PASS", "fix": "PASS"}, "test/locale/uk.test.js": {"run": "PASS", "test": "PASS", "fix": "PASS"}, "test/plugin/buddhistEra.test.js": {"run": "PASS", "test": "PASS", "fix": "PASS"}, "test/display.test.js": {"run": "PASS", "test": "PASS", "fix": "PASS"}, "test/plugin/devHelper.test.js": {"run": "PASS", "test": "PASS", "fix": "PASS"}, "test/locale/lt.test.js": {"run": "PASS", "test": "PASS", "fix": "PASS"}, "test/locale/zh-cn.test.js": {"run": "PASS", "test": "PASS", "fix": "PASS"}, "test/locale/ar.test.js": {"run": "PASS", "test": "PASS", "fix": "PASS"}, "test/plugin/isBetween.test.js": {"run": "PASS", "test": "PASS", "fix": "PASS"}}
{"test/plugin/customParseFormat.test.js": {"run": "PASS", "test": "FAIL", "fix": "PASS"}}
{"passed_count": 79, "failed_count": 0, "skipped_count": 0, "passed_tests": ["test/timezone.test.js:Add Time days (DST)", "test/locale/sk.test.js", "test/plugin/weekYear.test.js", "test/plugin/isSameOrBefore.test.js", "test/plugin/pluralGetSet.test.js", "test/timezone.test.js:Diff (DST)", "test/locale/keys.test.js", "test/parse.test.js", "test/plugin/weekday.test.js", "test/plugin/isLeapYear.test.js", "test/query.test.js", "test/plugin/localeData.test.js", "test/timezone.test.js:UTC diff in DST", "test/locale/zh.test.js", "test/plugin/declarations.test.js", "test/locale/bn.test.js", "test/plugin/dayOfYear.test.js", "test/locale/en.test.js", "test/get-set.test.js", "test/locale/he.test.js", "test/plugin/quarterOfYear.test.js", "test/plugin/objectSupport.test.js", "test/locale/fi.test.js", "test/plugin/utc-utcOffset.test.js", "test/locale/br.test.js", "test/locale/pl.test.js", "test/plugin/toObject.test.js", "test/plugin/isSameOrAfter.test.js", "test/plugin/weekOfYear.test.js", "test/plugin/calendar.test.js", "test/plugin/arraySupport.test.js", "test/plugin/isToday.test.js", "test/locale/hr.test.js", "test/locale.test.js", "test/plugin/customParseFormat.test.js", "test/plugin/duration.test.js", "test/plugin/isoWeeksInYear.test.js", "test/locale/uk.test.js", "test/locale/zh-cn.test.js", "test/plugin/isBetween.test.js", "test/plugin.test.js", "test/locale/de.test.js", "test/plugin/advancedFormat.test.js", "test/timezone.test.js", "test/utils.test.js", "test/plugin/relativeTime.test.js", "test/plugin/localizedFormat.test.js", "test/plugin/updateLocale.test.js", "test/constructor.test.js", "test/locale/ja.test.js", "test/plugin/timezone.test.js", "test/locale/ru.test.js", "test/timezone.test.js:UTC add day in DST", "test/manipulate.test.js", "test/locale/cs.test.js", "test/plugin/utc.test.js", "test/locale/sv.test.js", "test/plugin/toArray.test.js", "test/timezone.test.js:Utc Offset", "test/locale/bg.test.js", "test/locale/sr-cyrl.test.js", "test/plugin/isMoment.test.js", "test/plugin/isYesterday.test.js", "test/locale/sr.test.js", "test/plugin/preParsePostFormat.test.js", "test/comparison.test.js", "test/plugin/isTomorrow.test.js", "test/locale/et.test.js", "test/locale/hu.test.js", "test/timezone.test.js:UTC and utcOffset", "test/plugin/badMutable.test.js", "test/locale/sv-fi.test.js", "test/plugin/isoWeek.test.js", "test/plugin/minMax.test.js", "test/plugin/buddhistEra.test.js", "test/display.test.js", "test/plugin/devHelper.test.js", "test/locale/lt.test.js", "test/locale/ar.test.js"], "failed_tests": [], "skipped_tests": []}
{"passed_count": 78, "failed_count": 1, "skipped_count": 0, "passed_tests": ["test/timezone.test.js:Add Time days (DST)", "test/locale/sk.test.js", "test/plugin/weekYear.test.js", "test/plugin/isSameOrBefore.test.js", "test/plugin/pluralGetSet.test.js", "test/timezone.test.js:Diff (DST)", "test/locale/keys.test.js", "test/parse.test.js", "test/plugin/weekday.test.js", "test/plugin/isLeapYear.test.js", "test/query.test.js", "test/plugin/localeData.test.js", "test/timezone.test.js:UTC diff in DST", "test/locale/zh.test.js", "test/plugin/declarations.test.js", "test/locale/bn.test.js", "test/plugin/dayOfYear.test.js", "test/locale/en.test.js", "test/get-set.test.js", "test/locale/he.test.js", "test/plugin/quarterOfYear.test.js", "test/plugin/objectSupport.test.js", "test/locale/fi.test.js", "test/plugin/utc-utcOffset.test.js", "test/locale/br.test.js", "test/locale/pl.test.js", "test/plugin/toObject.test.js", "test/plugin/isSameOrAfter.test.js", "test/plugin/weekOfYear.test.js", "test/plugin/calendar.test.js", "test/plugin/arraySupport.test.js", "test/plugin/isToday.test.js", "test/locale/hr.test.js", "test/locale.test.js", "test/plugin/duration.test.js", "test/plugin/isoWeeksInYear.test.js", "test/locale/uk.test.js", "test/locale/zh-cn.test.js", "test/plugin/isBetween.test.js", "test/plugin.test.js", "test/locale/de.test.js", "test/plugin/advancedFormat.test.js", "test/timezone.test.js", "test/utils.test.js", "test/plugin/relativeTime.test.js", "test/plugin/localizedFormat.test.js", "test/plugin/updateLocale.test.js", "test/constructor.test.js", "test/locale/ja.test.js", "test/plugin/timezone.test.js", "test/locale/ru.test.js", "test/timezone.test.js:UTC add day in DST", "test/manipulate.test.js", "test/locale/cs.test.js", "test/plugin/utc.test.js", "test/locale/sv.test.js", "test/plugin/toArray.test.js", "test/timezone.test.js:Utc Offset", "test/locale/bg.test.js", "test/locale/sr-cyrl.test.js", "test/plugin/isMoment.test.js", "test/plugin/isYesterday.test.js", "test/locale/sr.test.js", "test/plugin/preParsePostFormat.test.js", "test/comparison.test.js", "test/locale/et.test.js", "test/plugin/isTomorrow.test.js", "test/locale/hu.test.js", "test/timezone.test.js:UTC and utcOffset", "test/plugin/badMutable.test.js", "test/locale/sv-fi.test.js", "test/plugin/isoWeek.test.js", "test/plugin/minMax.test.js", "test/plugin/buddhistEra.test.js", "test/display.test.js", "test/plugin/devHelper.test.js", "test/locale/lt.test.js", "test/locale/ar.test.js"], "failed_tests": ["test/plugin/customParseFormat.test.js"], "skipped_tests": []}
{"passed_count": 79, "failed_count": 0, "skipped_count": 0, "passed_tests": ["test/timezone.test.js:Add Time days (DST)", "test/locale/sk.test.js", "test/plugin/weekYear.test.js", "test/plugin/isSameOrBefore.test.js", "test/plugin/pluralGetSet.test.js", "test/timezone.test.js:Diff (DST)", "test/locale/keys.test.js", "test/parse.test.js", "test/plugin/weekday.test.js", "test/plugin/isLeapYear.test.js", "test/query.test.js", "test/plugin/localeData.test.js", "test/timezone.test.js:UTC diff in DST", "test/locale/zh.test.js", "test/plugin/declarations.test.js", "test/locale/bn.test.js", "test/plugin/dayOfYear.test.js", "test/locale/en.test.js", "test/locale/he.test.js", "test/get-set.test.js", "test/plugin/quarterOfYear.test.js", "test/plugin/objectSupport.test.js", "test/locale/fi.test.js", "test/plugin/utc-utcOffset.test.js", "test/locale/br.test.js", "test/locale/pl.test.js", "test/plugin/toObject.test.js", "test/plugin/isSameOrAfter.test.js", "test/plugin/weekOfYear.test.js", "test/plugin/calendar.test.js", "test/plugin/arraySupport.test.js", "test/plugin/isToday.test.js", "test/locale/hr.test.js", "test/locale.test.js", "test/plugin/customParseFormat.test.js", "test/plugin/duration.test.js", "test/plugin/isoWeeksInYear.test.js", "test/locale/uk.test.js", "test/locale/zh-cn.test.js", "test/plugin/isBetween.test.js", "test/plugin.test.js", "test/locale/de.test.js", "test/plugin/advancedFormat.test.js", "test/timezone.test.js", "test/utils.test.js", "test/plugin/relativeTime.test.js", "test/plugin/localizedFormat.test.js", "test/plugin/updateLocale.test.js", "test/constructor.test.js", "test/locale/ja.test.js", "test/plugin/timezone.test.js", "test/locale/ru.test.js", "test/timezone.test.js:UTC add day in DST", "test/manipulate.test.js", "test/locale/cs.test.js", "test/plugin/utc.test.js", "test/locale/sv.test.js", "test/plugin/toArray.test.js", "test/timezone.test.js:Utc Offset", "test/locale/bg.test.js", "test/locale/sr-cyrl.test.js", "test/plugin/isMoment.test.js", "test/plugin/isYesterday.test.js", "test/locale/sr.test.js", "test/plugin/preParsePostFormat.test.js", "test/comparison.test.js", "test/plugin/isTomorrow.test.js", "test/locale/et.test.js", "test/locale/hu.test.js", "test/timezone.test.js:UTC and utcOffset", "test/plugin/badMutable.test.js", "test/locale/sv-fi.test.js", "test/plugin/isoWeek.test.js", "test/plugin/minMax.test.js", "test/plugin/buddhistEra.test.js", "test/display.test.js", "test/plugin/devHelper.test.js", "test/locale/lt.test.js", "test/locale/ar.test.js"], "failed_tests": [], "skipped_tests": []}