Simulcast, Screen sharing & Various improvements (#4)

* Respect `RTCIceTransportPolicy` enum and organize

* Simplify syntax where possible etc.

* Combine `VideoPreset` and `VideoPresets`

* Default values for `ConnectOptions`

* Build URI instead of String manipulation

* Slight modifications to Exception

* `LiveKitTheme` for example

* `VideoEncoding` class

* Organize imports

* First simulcast implementation

* Remove unnecessary try-catches

* Update Android settings

* Remember uri and token

* example improvements

* `fit` parameter for VideoTrackRenderer

* Simulcast option for example

* Pass `defaultPublishOptions`

* Show only `VideoQuality`

* Pass tests

* Better buildUri logic

* Named parameter to positional

* Explicit imports

* `VideoParameter` instead of `VideoPreset`

* Use `mediaTrack.getSettings` when possible

* Safer dispose logic

* Safer `PCTransport`

Update transport.dart

* Synchronized events for `SignalClient`

* Use logger instead of print

* Make example compile for iOS

* First screen share implementation

* Make example work with screen share

* Example improvement

* Code optimization

* Don't depend on web_socket_channel

* Fix: Unpublish track bug

* Show participant mute state & identity

* Update protos

* Remote mute/unmute

* iOS Background mode

* Separate `createCameraTrack` and `createScreenTrack`

* Clean up

* PB fix

* format

* Fix analyzer warning

* Android clean up

* Update README.md

* Clean up

example/lib/main.dart

@@ -1,7 +1,8 @@
 import 'package:flutter/material.dart';
+import 'package:livekit_example/theme.dart';
 import 'package:logging/logging.dart';
-import 'package:livekit_client/livekit_client.dart';
-import 'room.dart';
+
+import 'pages/connect.dart';
 
 void main() {
   // configure logs for debugging
@@ -10,113 +11,21 @@ void main() {
     print('${record.level.name}: ${record.time}: ${record.message}');
   });
 
-  runApp(const MyApp());
+  WidgetsFlutterBinding.ensureInitialized();
+
+  runApp(const LiveKitExampleApp());
 }
 
-class MyApp extends StatelessWidget {
+class LiveKitExampleApp extends StatelessWidget {
   //
-  const MyApp({
+  const LiveKitExampleApp({
     Key? key,
   }) : super(key: key);
 
   @override
   Widget build(BuildContext context) => MaterialApp(
-        title: 'LiveKit Demo',
-        theme: ThemeData(
-          primarySwatch: Colors.deepPurple,
-        ),
-        home: const PreConnectWidget(
-          url: '<livekit_host>',
-          token: '<access_token>',
-        ),
-      );
-}
-
-class PreConnectWidget extends StatefulWidget {
-  //
-  final String url;
-  final String token;
-
-  const PreConnectWidget({
-    required this.url,
-    required this.token,
-    Key? key,
-  }) : super(key: key);
-
-  @override
-  State<StatefulWidget> createState() => _PreConnectWidgetState();
-}
-
-class _PreConnectWidgetState extends State<PreConnectWidget> {
-  //
-  final _urlCtrl = TextEditingController();
-  final _tokenCtrl = TextEditingController();
-
-  @override
-  void initState() {
-    super.initState();
-    _urlCtrl.text = widget.url;
-    _tokenCtrl.text = widget.token;
-  }
-
-  @override
-  void dispose() {
-    _urlCtrl.dispose();
-    _tokenCtrl.dispose();
-    super.dispose();
-  }
-
-  void _connect(BuildContext context) async {
-    try {
-      print('Connecting with url: ${_urlCtrl.text}, token: ${_tokenCtrl.text}...');
-
-      final room = await LiveKitClient.connect(
-        _urlCtrl.text,
-        _tokenCtrl.text,
-      );
-
-      Navigator.push<void>(
-        context,
-        MaterialPageRoute(builder: (context) {
-          return RoomWidget(room);
-        }),
-      );
-    } catch (e) {
-      print('could not connect $e');
-    }
-  }
-
-  @override
-  Widget build(BuildContext context) => Scaffold(
-        appBar: AppBar(
-          title: const Text('Connect to LiveKit'),
-        ),
-        body: Center(
-          child: Container(
-            // width: 250,
-            alignment: Alignment.center,
-            margin: const EdgeInsets.all(10),
-            child: Column(
-              children: [
-                TextField(
-                  controller: _urlCtrl,
-                  decoration: const InputDecoration(
-                    labelText: 'URL',
-                  ),
-                ),
-                TextField(
-                  controller: _tokenCtrl,
-                  decoration: const InputDecoration(
-                    labelText: 'Token',
-                  ),
-                ),
-                TextButton(
-                  onPressed: () => _connect(context),
-                  child: const Text('Connect'),
-                ),
-              ],
-            ),
-          ),
-        ),
+        title: 'LiveKit Flutter Example',
+        theme: LiveKitTheme().buildThemeData(context),
+        home: const ConnectPage(),
       );
 }