Element Call video rooms (#9267)

* Add an element_call_url config option

* Add a labs flag for Element Call video rooms

* Add Element Call as another video rooms backend

* Consolidate event power level defaults

* Remember to clean up participantsExpirationTimer

* Fix a code smell

* Test the clean method

* Fix some strict mode errors

* Test that clean still works when there are no state events

* Test auto-approval of Element Call widget capabilities

* Deduplicate some code to placate SonarCloud

* Fix more strict mode errors

* Test that calls disconnect when leaving the room

* Test the get methods of JitsiCall and ElementCall more

* Test Call.ts even more

* Test creation of Element video rooms

* Test that createRoom works for non-video-rooms

* Test Call's get method rather than the methods of derived classes

* Ensure that the clean method is able to preserve devices

* Remove duplicate clean method

* Fix lints

* Fix some strict mode errors in RoomPreviewCard

* Test RoomPreviewCard changes

* Quick and dirty hotfix for the community testing session

* Revert "Quick and dirty hotfix for the community testing session"

This reverts commit 37056514fbc040aaf1bff2539da770a1c8ba72a2.

* Fix the event schema for org.matrix.msc3401.call.member devices

* Remove org.matrix.call_duplicate_session from Element Call capabilities

It's no longer used by Element Call when running as a widget.

* Replace element_call_url with a map

* Make PiPs work for virtual widgets

* Auto-approve room timeline capability

Because Element Call uses this now

* Create a reusable isVideoRoom util

src/utils/WidgetUtils.ts

@@ -482,8 +482,8 @@ export default class WidgetUtils {
         appId: string,
         app: Partial<IApp>,
         senderUserId: string,
-        roomId: string | null,
-        eventId: string,
+        roomId: string | undefined,
+        eventId: string | undefined,
     ): IApp {
         if (!senderUserId) {
             throw new Error("Widgets must be created by someone - provide a senderUserId");