Add WakeLock to dismiss ringing call screen when call is cancelled (#4478)

* Add `WakeLock` to dismiss ringing call screen when call is cancelled

We had already some checks in place to automatically cancel a ringing call notification/screen when the call was no longer active, but the `RoomInfo` updates weren't being processed because the app was 'paused'.

The partial wakelock should ensure these room info updates are handled.

* Add mutual exclusion to `ActiveCallManager` methods to improve thread safety

libraries/push/impl/src/main/kotlin/io/element/android/libraries/push/impl/push/DefaultPushHandler.kt

@@ -118,7 +118,7 @@ class DefaultPushHandler @Inject constructor(
         }
     }
 
-    private fun handleRingingCallEvent(notifiableEvent: NotifiableRingingCallEvent) {
+    private suspend fun handleRingingCallEvent(notifiableEvent: NotifiableRingingCallEvent) {
         Timber.i("## handleInternal() : Incoming call.")
         elementCallEntryPoint.handleIncomingCall(
             callType = CallType.RoomCall(notifiableEvent.sessionId, notifiableEvent.roomId),