fix: switching between 'subtitles' and 'captions' text tracks is broken

[alex-barstow]

Description

This fixes a regression introduced in v7.4.3. The addition of this code made it so that, when turning on captions, other text tracks are only disabled if they are of the same kind as the one being selected. This resulted in broken behavior when switching between a subtitles track and a captions track or vice-versa.

Specific Changes proposed

"Subtitle" tracks should be disabled if another "caption" track is enabled, and vice-versa (in other words, they should be considered the same when enabling/disabling tracks). There is existing infrastructure that stores the appropriate text track kinds_ or kind_ for a given instance of TextTrackButton, each of which creates a list of TextTrackMenuItem instances. We can pass that information on to each instance of TextTrackMenuItem where it can be stored as a property and used to aid in text track enabling/disabling decisions.

Requirements Checklist

• Feature implemented / Bug fixed
• If necessary, more likely in a feature request than a bug fix
  • Change has been verified in an actual browser (Chome, Firefox, IE)
  • Unit Tests updated or fixed
  • Docs/guides updated
  • Example created (starter template on JSBin)
• Reviewed by Two Core Contributors

[gkatsev]

Verified this as well.