feat(TextTrackInfo) Passthrough roles even if dash can't parse them

Created by: justinanastos

Assuming an AdaptionSet has roles defined, the only way to access them is via MediaPlayer#getTracksFor('text'). If the manifest is using fragmented text, then MediaPlayer#getTracksFor('text') will return [] and the only way to get the text track list is to listen for TEXT_TRACKS_ADDED. However, the tracks in the TEXT_TRACKS_ADDED event is TextTrackInfo[], which does not include the original roles.

This will pass through whatever roles are parsed, allowing them to be accessed for all text track types.

Possibly a workaround for #1236 (closed)