Explore multiple languages in webvtt

[kimpham54]

https://w3c.github.io/webvtt/#cue-text
https://w3c.github.io/webvtt/#css-extensions-introduction -> look at the Type selector example

so you could do something like

WEBVTT

00:00:00.000 --> 00:00:08.000
<lang en>Yellow!</lang>
<lang fr>Yellow!</lang>

00:00:09.000 --> 00:00:15.000
<lang en>Blue!</lang>
<lang fr>Blue!</lang>

From @Natkeeran: One VTT can contain cues for different languages and different tracks will specify the language selection

The applicable language for the list of WebVTT Node Objects can be set by the srclang attribute in HTML.

<video ...>
 <track src="example-attr.vtt"
        srclang="en-US" default>
</video>

[kstapelfeldt]

If we could do this it would be a cleaner solution than our existing solution, which relies on file-level naming conventions. We don't have a local use case for this and it could be a large issue/task, so it may be something we should explore in the refactor for CLAW. Do browsers support this feature in WebVTT? (video.js) Can we support all languages in one webvtt file? This is a backburner issue for us for exploration.

[MarcusBarnes]

Added the large label to reflect that the work revolves around larger architectural and design discussions of how to support language features and with what kinds of file formats for transcripts.