* Update our cancel icon
The cancel icon we're using in the app has drifted out of sync with the ones used in our designs. We also had two identical-looking icons, so this consolidates them into one.
I've simultaneously updated our chevron icons, since in the case of the 'jump to unread' timeline button, it became clear that the weight of the new close icon did not match the thinner chevron.
* Don't squish bottom/top-aligned tooltips near the edge of the screen
* Close the timeline panel when returning to the fullscreen timeline view
* Add layout switching capabilities to ElementCall
* Bring the room header in line with the group call designs
* Bring the PiP header in line with the group call designs
* Fix lints
* Clarify tooltip CSS calculations
* Test PipView
* Expand RoomHeader test coverage
* Test PipView more
* Fix device selection in pre-join screen for Element Call video rooms
As per https://github.com/vector-im/element-call/pull/609
* Update unit test
* Lint
* Hold a media stream while we enumerate device so we can do so reliably.
This means we can remove the device fallback labels.
* i18n
* Remove unnecessary useState
* Fix fetching video devices when video muted
* Actually fix preview stream code
* Fix unit test now fallback is no longer a thing
* Test changing devices
* Create m.room calls in video rooms, and m.prompt calls otherwise
* Terminate a call when the last person leaves
* Hook up the room header button to a unified CallView component
* Write more tests
