This is a follow-up to this fix in VHS, after which default in-manifest subtitles were still not being correctly enabled. The reason is because Video.js's text track preselection logic was running before the media groups were set up in VHS.
Text track preselection should happen on `loadedmetadata` instead of `loadstart`. According to the HTML spec, text track data is available on `loadedmetadata`, so we should be waiting until then to make preselection decisions.
When preselecting a new track based on user preference, make sure that the language is actually set and that the track we're testing is either a captions or a subtitles track.
Fixes#5553
When providing the TextTrackDisplay component with track settings overrides, currently colour codes with only three digits are supported. This updates it so that 6 digit hex codes are also accepted.
A we retained a lot of references to DOM elements in various components. Here we clear it up. Also, make sure that we remove unused listeners as they can retain objects as well.
Update evented mixin to null out the eventBusEl_ after the component is disposed.
Add a feature for components, to tell it not to auto-initialize the evented mixin.
Re-enable the tests that were removed in #4640.
