* Use native js-sdk group call support
Now that the js-sdk supports group calls natively, our group call implementation can be simplified a bit. Switching to the js-sdk implementation also brings the react-sdk up to date with recent MSC3401 changes, and adds support for joining calls from multiple devices. (So, the previous logic which sent to-device messages to prevent multi-device sessions is no longer necessary.)
* Fix strings
* Fix strict type errors
* 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
