fix: audio play bug for ios safari. (#285)

* fix: audio play bug for ios safari. (WIP).

* chore: Repair and can pop up the playback prompt dialog box correctly.

* chore: add AudioContext to reduce playback delay.

lib/src/internal/events.dart

@@ -61,6 +61,22 @@ class TrackStreamUpdatedEvent with TrackEvent, InternalEvent {
   });
 }
 
+@internal
+class AudioPlaybackStarted with TrackEvent, EngineEvent, InternalEvent {
+  final Track track;
+  const AudioPlaybackStarted({
+    required this.track,
+  });
+}
+
+@internal
+class AudioPlaybackFailed with TrackEvent, EngineEvent, InternalEvent {
+  final Track track;
+  const AudioPlaybackFailed({
+    required this.track,
+  });
+}
+
 @internal
 class LocalTrackOptionsUpdatedEvent with TrackEvent, InternalEvent {
   final LocalTrack track;