Show a lobby screen in video rooms (#8287)

* Show a lobby screen in video rooms

* Add connecting state

* Test VideoRoomView

* Test VideoLobby

* Get the local video stream with useAsyncMemo

* Clean up code review nits

* Explicitly state what !important is overriding

* Use spacing variables

* Wait for video channel messaging

* Update join button copy

* Show frame on both the lobby and widget

* Force dark theme for video lobby

* Wait for the widget to be ready

* Make VideoChannelStore constructor private

* Allow video lobby to shrink

* Add invite button to video room header

* Show connected members on lobby screen

* Make avatars in video lobby clickable

* Increase video channel store timeout

* Fix Jitsi Meet getting wedged on startup in Chrome and Safari

* Revert "Fix Jitsi Meet getting wedged on startup in Chrome and Safari"

This reverts commit 9f77b8c227.

* Disable device buttons while connecting

* Factor RoomFacePile into a separate file

* Fix i18n lint

* Fix switching video channels while connected

* Properly limit number of connected members in face pile

* Fix CSS lint

res/css/views/elements/_FacePile.scss

@@ -20,7 +20,8 @@ limitations under the License.
         flex-direction: row-reverse;
         vertical-align: middle;
 
-        > .mx_FacePile_face + .mx_FacePile_face {
+        // Overlap the children
+        > * + * {
             margin-right: -8px;
         }