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

example/lib/exts.dart

@@ -20,6 +20,24 @@ extension LKExampleExt on BuildContext {
         ),
       );
 
+  Future<bool?> showUnPublishDialog() => showDialog<bool>(
+        context: this,
+        builder: (ctx) => AlertDialog(
+          title: const Text('UnPublish'),
+          content: const Text('Would you like to un-publish your Camera & Mic ?'),
+          actions: [
+            TextButton(
+              onPressed: () => Navigator.pop(ctx, false),
+              child: const Text('NO'),
+            ),
+            TextButton(
+              onPressed: () => Navigator.pop(ctx, true),
+              child: const Text('YES'),
+            ),
+          ],
+        ),
+      );
+
   Future<void> showErrorDialog(dynamic exception) => showDialog<void>(
         context: this,
         builder: (ctx) => AlertDialog(