Gate support for certain EOTFs/primaries/matrices on color management / hdr flags

Creates a new class VideoColorSpace specifically for encoding color spaces
according to ISO/IEC 23001-8.

Plumb this color space through from parsing to validation.

BUG=687627

Review-Url: https://codereview.chromium.org/2742113002
Cr-Commit-Position: refs/heads/master@{#456518}
  TestKeySystemProperties(const std::string& key_system_name)
      : key_system_name_(key_system_name) {}

  TestKeySystemProperties(const std::string& key_system_name)
      : key_system_name_(key_system_name) {}
