feat(a11y): make (most) UI elements reachable via keyboard

Remove global variables from files
Change type to interface

Remove comments referencing InlineDialog

Convert Popover to TS
Update OverflowMenu to use Popover instead of InlineDialog

Update video thumbnail design
Update design of indicators
In filmstrip view move Screen Sharing indicator to the top
Removed dominant speaker indicator
Use ContextMenu component for the connection stats popover
Combine Remove video menu and Meeting participant context menu into one component
Moved some styles from SCSS to JSS
Fix mobile avatars too big
Fix mobile horizontal scroll
Created button for Send to breakout room action

Clicking on an item when the popup drawer is displayed would keep it open.
Now clicking on any item should automatically close the drawer.

Popup was also refactored and no longer uses refs.

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

- on ipads, long touch open dialog now opens the context menu to the left of the thumbnail as expected
- on ipads, now we close context menus on tap out
- fix case when participant context menu's height > tileview videos' height causing scroll on videos pane
- keep toolbox open while the overflow menu is shown
- keep remote participant video thumbnail in filmstrip visible even if toolbox is hidden, if context menu is opened
- Fix bug where toolbox could be completely disabled

- hide toolbars only when in tile view
- fix community issue: https://github.com/jitsi/jitsi-meet/issues/9818

- long touch on thumbnail opens context menu
- hide context menu icon
- add button for connection info to context menu

* Make Jitsi WCAG 2.1 compliant

* Fixed password form keypress handling

* Added keypress handler to name form

* Removed unneccessary dom query

* Fixed mouse hove style

* Removed obsolete css rules

* accessibilty background feature

* Merge remote-tracking branch 'upstream/master' into nic/fix/merge-conflicts

* fix error

* add german translation

* Fixed merge issue

* Add id prop back to device selection

* Fixed lockfile

Co-authored-by: AHMAD KADRI <52747422+ahmadkadri@users.noreply.github.com>

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

For the most part the changes are taking the "static propTypes" declaration off
of components and declaring them as Flow types. Sometimes to support flow some
method signatures had to be added. There are some exceptions in which more had
to be done to tame the beast:
- AbstractVideoTrack: put in additional truthy checks for videoTrack.
- Video: add truthy checks for the _videoElement ref.
- shouldRenderVideoTrack function: Some component could pass null for the
  videoTrack argument and Flow wanted that called out explicitly.
- DisplayName: Add a truthy check for the input ref before acting on it.
- NumbersList: Move array checks inline for Flow to comprehend array methods
  could be called. Add type checks in the Object.entries loop as the value is
  assumed to be a mixed type by Flow.
- AbstractToolbarButton: add additional truthy check for passed in type.

* ref(popover): allow for popover content from the right

Popovers contents can display to the left of the trigger
and above the trigger. Add the ability to display to the
right of the trigger my adding mouseover padding. This
may be needed for tile view, depending on where the triggers
are located.

* squash: abstract common css proprties into placeholder class

Prepare for React 16.