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

* audio mixing pref

* lint

modules/expo-bluesky-swiss-army/ios/PlatformInfo/ExpoPlatformInfoModule.swift

@@ -7,5 +7,15 @@ public class ExpoPlatformInfoModule: Module {
     Function("getIsReducedMotionEnabled") {
       return UIAccessibility.isReduceMotionEnabled
     }
+
+    Function("setAudioMixWithOthers") { (mixWithOthers: Bool) in
+      var options: AVAudioSession.CategoryOptions
+      if mixWithOthers {
+        options = [.mixWithOthers]
+      } else {
+        options = []
+      }
+      try? AVAudioSession.sharedInstance().setCategory(AVAudioSession.Category.playback, mode: .default, options: options)
+    }
   }
 }