Convert AV Moderation and Breakout Rooms to TS

- implement breakout-rooms
- integrated into the participants panel
- managed by moderators
- moderators can send participants to breakout-rooms
- participants can join breakout rooms by themselve
- participants can leave breakout rooms anytime

Co-authored-by: Robert Pintilii <robert.pin9@gmail.com>
Co-authored-by: Saúl Ibarra Corretgé <saghul@jitsi.org>