Refactor media devices to live outside React as Observables (#3334)

* Refactor media devices to live outside React as Observables

This moves the media devices state out of React to further our transition to a MVVM architecture in which we can more easily model and store complex application state. I have created an AppViewModel to act as the overarching state holder for any future non-React state we end up creating, and the MediaDevices reside within this. We should move more application logic (including the CallViewModel itself) there in the future.

* Address review feedback

* Fixes from ios debugging session: (#3342)

- dont use preferred vs selected concept in controlled media. Its not needed since we dont use the id for actual browser media devices (the id's are not even actual browser media devices)
  - add more logging
  - add more conditions to not accidently set a deviceId that is not a browser deviceId but one provided via controlled.

---------

Co-authored-by: Timo <16718859+toger5@users.noreply.github.com>

src/utils/observable.ts

@@ -38,3 +38,18 @@ export function accumulate<State, Event>(
   return (events$: Observable<Event>): Observable<State> =>
     events$.pipe(scan(update, initial), startWith(initial));
 }
+
+/**
+ * Reads the current value of a state Observable without reacting to future
+ * changes.
+ *
+ * This function exists to help with certain cases of bridging Observables into
+ * React, where an initial value is needed. You should never use it to create an
+ * Observable derived from another Observable; use reactive operators instead.
+ */
+export function getValue<T>(state$: Observable<T>): T {
+  let value: T | typeof nothing = nothing;
+  state$.subscribe((x) => (value = x)).unsubscribe();
+  if (value === nothing) throw new Error("Not a state Observable");
+  return value;
+}

src/utils/test.ts

@@ -46,6 +46,7 @@ import {
   type ResolvedConfigOptions,
 } from "../config/ConfigOptions";
 import { Config } from "../config/Config";
+import { type MediaDevices } from "../state/MediaDevices";
 
 export function withFakeTimers(continuation: () => void): void {
   vi.useFakeTimers();
@@ -332,3 +333,18 @@ export const mockTrack = (identity: string): TrackReference =>
     track: {},
     source: {},
   }) as unknown as TrackReference;
+
+export const deviceStub = {
+  available$: of(new Map<never, never>()),
+  selected$: of(undefined),
+  select(): void {},
+};
+
+export function mockMediaDevices(data: Partial<MediaDevices>): MediaDevices {
+  return {
+    audioInput: deviceStub,
+    audioOutput: deviceStub,
+    videoInput: deviceStub,
+    ...data,
+  } as MediaDevices;
+}