RoomVC: Media selection don’t work using VoiceOver

When selecting a media in the timeline several issues occur:
- wrong media is displayed
- VoiceOver look at element behind the presented media
- No possibility to access video controls

Start by reproducing media selection in the timeline with VoiceOver and observe which media is presented, where focus lands, and whether video controls are reachable. Done means the selected media is displayed, VoiceOver focuses the presented media rather than the element behind it, and the video controls can be accessed.

Written by the indexing model from the issue text.