Fix device selection in pre-join screen for Element Call video rooms (#9321)

* Fix device selection in pre-join screen for Element Call video rooms

As per https://github.com/vector-im/element-call/pull/609

* Update unit test

* Lint

* Hold a media stream while we enumerate device so we can do so reliably.

This means we can remove the device fallback labels.

* i18n

* Remove unnecessary useState

* Fix fetching video devices when video muted

* Actually fix preview stream code

* Fix unit test now fallback is no longer a thing

* Test changing devices

test/models/Call-test.ts

@@ -616,8 +616,8 @@ describe("ElementCall", () => {
             await call.connect();
             expect(call.connectionState).toBe(ConnectionState.Connected);
             expect(messaging.transport.send).toHaveBeenCalledWith(ElementWidgetActions.JoinCall, {
-                audioInput: "1",
-                videoInput: "2",
+                audioInput: "Headphones",
+                videoInput: "Built-in webcam",
             });
         });