Audio device controls for mobile native audio device selection

Backport of 0971a15c40.

src/state/MuteAllAudioModel.ts

@@ -0,0 +1,19 @@
+/*
+Copyright 2025 New Vector Ltd.
+
+SPDX-License-Identifier: AGPL-3.0-only OR LicenseRef-Element-Commercial
+Please see LICENSE in the repository root for full details.
+*/
+
+import { combineLatest, startWith } from "rxjs";
+
+import { setAudioEnabled$ } from "../controls";
+import { muteAllAudio as muteAllAudioSetting } from "../settings/settings";
+
+/**
+ * This can transition into sth more complete: `GroupCallViewModel.ts`
+ */
+export const muteAllAudio$ = combineLatest(
+  [setAudioEnabled$.pipe(startWith(true)), muteAllAudioSetting.value$],
+  (outputEnabled, settingsMute) => !outputEnabled || settingsMute,
+);