Currently just by adding /holdcall and /unholdcall slash commands
The only place the hold status of the call is currently represented
is when the call is a voice call and you're viewing a different room:
it's not wired up when you're viewing the room because that currently
uses the room status bar which it won't do with the new UI.
Also convert VideoFeed to typescript, and remove videoview because
it essentially just managed the fullscreen functionality, but we'll
want and 'on hold' representation (and probably chrome for hagnup etc)
in the fullscreen UI too, so let's just make CallView the thing that
gets fullscreened.
* Similar sizing
* Fix pointers so the jitsi widget doesn't feel clickable when it's not
* We might want to introduce click-to-visit-room for the Jitsi widget (like the 1:1 call), however the Jitsi widget has many more controls to worry about
* Remove the menu bar from the widget to avoid accidents
