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/track/track.dart

@@ -1,13 +1,17 @@
+import 'package:flutter/material.dart';
 import 'package:flutter_webrtc/flutter_webrtc.dart' as rtc;
-import 'package:livekit_client/src/classes/change_notifier.dart';
+import 'package:meta/meta.dart';
 import 'package:uuid/uuid.dart';
 
+import '../extensions.dart';
+import '../logger.dart';
 import '../proto/livekit_models.pb.dart' as lk_models;
+import '../support/disposable.dart';
 
 /// Wrapper around a MediaStreamTrack with additional metadata.
 /// Base for [AudioTrack] and [VideoTrack],
 /// can not be instantiated directly.
-abstract class Track extends LKChangeNotifier {
+abstract class Track extends DisposableChangeNotifier {
   static const cameraName = 'camera';
   static const screenShareName = 'screen';
 
@@ -19,6 +23,10 @@ abstract class Track extends LKChangeNotifier {
   rtc.RTCRtpTransceiver? transceiver;
   String? _cid;
 
+  // started / stopped
+  bool _active = false;
+  bool get isActive => _active;
+
   Track(
     this.kind,
     this.name,
@@ -50,7 +58,33 @@ abstract class Track extends LKChangeNotifier {
     return cid;
   }
 
-  Future<void> stop() async {
-    await mediaStreamTrack.stop();
+  // returns true if started, false if already started
+  @mustCallSuper
+  Future<bool> start() async {
+    if (_active) {
+      // already started
+      return false;
+    }
+
+    _active = true;
+    return true;
+  }
+
+  // returns true if stopped, false if already stopped
+  @mustCallSuper
+  Future<bool> stop() async {
+    if (!_active) {
+      // already stopped
+      return false;
+    }
+
+    try {
+      await mediaStreamTrack.stop();
+    } catch (_) {
+      logger.warning('[$objectId] rtc.mediaStreamTrack.stop() did throw ${_}');
+    }
+
+    _active = false;
+    return true;
   }
 }