[Videos] Add iOS function to set AVAudioSession.CategoryOptions to .mixWithOthers (#4905)

* audio mixing pref

* lint

modules/expo-bluesky-swiss-army/src/PlatformInfo/index.ts

@@ -3,3 +3,7 @@ import {NotImplementedError} from '../NotImplemented'
 export function getIsReducedMotionEnabled(): boolean {
   throw new NotImplementedError()
 }
+
+export function setAudioMixWithOthers(mixWithOthers: boolean): void {
+  throw new NotImplementedError({mixWithOthers})
+}