Session migration (#72)

* impl

* retry logic

* simulate

* pass checks

* adjust log level

* retry condition

* fix simulate scenario params

* format

* use `RTCPeerConnectionState` instead of `RTCIceConnectionState`

* adjust retry

* additional check for completer

* more logging

* fix id

* pub

* change package

* doc update

* retry tests

* format

* apply suggestions

example/lib/main.dart

@@ -2,10 +2,9 @@ import 'package:flutter/material.dart';
 import 'package:livekit_example/theme.dart';
 import 'package:logging/logging.dart';
 import 'package:intl/intl.dart';
-
 import 'pages/connect.dart';
 
-void main() {
+void main() async {
   final format = DateFormat('HH:mm:ss');
   // configure logs for debugging
   Logger.root.level = Level.FINE;