Add voice broadcast permissions (#9284)

* Add Voice Broadcast labs setting and composer button

* Implement strict typing

* Extend MessageComposer-test

* Extend tests

* Revert some strict type fixex

* Implement voice broadcast permissions

* Update variable casing

src/contexts/RoomContext.ts

@@ -45,6 +45,7 @@ const RoomContext = createContext<IRoomState>({
     canReact: false,
     canSelfRedact: false,
     canSendMessages: false,
+    canSendVoiceBroadcasts: false,
     resizing: false,
     layout: Layout.Group,
     lowBandwidth: false,