Better audio management (#10)

* add audio_session package

* `AudioManager` initial design

* try to integrate audio manager

* configure audio session

* `DisposeAware`

disposing if already published causes exception.

* organize

* guard flutter_webrtc calls

* websocket async fix

* use `ConnectionState` instead of `_isClosed` and `isReconnecting`

* change create audio track defaults

* update protos

* protocol 3 speaker updates

* fix exception

* emit `RoomDisconnectedEvent` only once

* fix exception

* keep track of local / remote audio tracks

* explicit types

* manage track state

* re-structure audio management

* change defaults

* unpublish all

* use experimental build

* change defaults

* configuring is optional

* call native `RTCAudioSession.setConfiguration`

* defaults adjustment

* iOS only for now

* use lib 92.4515.07

* clean up

* revert audio options for now

* remove pod source

* rename apple related audio

* `createListener` method

* organize native audio

* `SpeakingChangedEvent` only on `Participant`

* refactoring

* fix ios compile

* fix configure audio only for iOS logic

* minor fix & clean up

* change dispose logic

* format protos

* fix unpublishTrack

* `createListener` into a mixin

* simplify

* use flutter_webrtc master

* unpublish for example

* update ios icon

* android icon

* web icon

* favicon

lib/src/participant/remote_participant.dart

@@ -90,8 +90,10 @@ class RemoteParticipant extends Participant {
     final Track track;
     if (pub.kind == lk_models.TrackType.AUDIO) {
       // audio track
+      // await AudioManager().incrementSubscriptionCounter();
+
       final audioTrack = AudioTrack(pub.name, mediaTrack, stream);
-      audioTrack.start();
+      await audioTrack.start();
       track = audioTrack;
     } else {
       // video track
@@ -143,8 +145,7 @@ class RemoteParticipant extends Participant {
 
     // unpublish any track that is not in the info
     final validSids = info.tracks.map((e) => e.sid);
-    final removeSids =
-        trackPublications.values.where((e) => !validSids.contains(e.sid)).map((e) => e.sid);
+    final removeSids = trackPublications.keys.where((e) => !validSids.contains(e)).toSet();
     for (final sid in removeSids) {
       await unpublishTrack(sid, notify: true);
     }
@@ -165,6 +166,10 @@ class RemoteParticipant extends Participant {
         track: track,
         publication: pub,
       ));
+
+      // if (track is AudioTrack) {
+      //   await AudioManager().decrementSubscriptionCounter();
+      // }
     }
 
     if (notify) {