This is a stop-gap approach to remove the AtlasKit notifications stack.

Instead of using a AK FlagGroup to render our notifications (Flag components)
in, create our own container and use a fake FlagGroupContext provider, which is
what FlagGroup uses to control what flags can be dismissed.

Since we now render all notifications, the web part has been refactored to make
sure all notifications get a timer.

Added animations

Renamed DrawerPortal to JitsiPortal

Redesigned notifications
Changed notification text and icons color and added collared ribbon

* Implement opening toolbar and participant overflows as drawers when below certain width.
* Fix dial-in copy button displaying incorrectly.