- add possibility to allow execution of the button's routine besides triggering
`toolbarButtonClicked` API event
- keep backwards compatibility
- get rid of `ToolbarButton`
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
Contributing all buttons in one place goes against the designs that we
set out at the beginning of the project's rewrite and that multiple of
us have been following since then.