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

* audio mixing pref

* lint

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

@@ -1,6 +1,12 @@
+import {NotImplementedError} from '../NotImplemented'
+
 export function getIsReducedMotionEnabled(): boolean {
   if (typeof window === 'undefined') {
     return false
   }
   return window.matchMedia('(prefers-reduced-motion: reduce)').matches
 }
+
+export function setAudioMixWithOthers(mixWithOthers: boolean): void {
+  throw new NotImplementedError({mixWithOthers})
+}