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/android/app/build.gradle

@@ -32,14 +32,14 @@ android {
         main.java.srcDirs += 'src/main/kotlin'
     }
 
-    compileOptions {
-        sourceCompatibility JavaVersion.VERSION_1_8
-        targetCompatibility JavaVersion.VERSION_1_8
-    }
+    // compileOptions {
+    //     sourceCompatibility JavaVersion.VERSION_1_8
+    //     targetCompatibility JavaVersion.VERSION_1_8
+    // }
 
     defaultConfig {
         // TODO: Specify your own unique Application ID (https://developer.android.com/studio/build/application-id.html).
-        applicationId "io.livekit.flutter_example"
+        applicationId "io.livekit.example"
         minSdkVersion 21
         targetSdkVersion 30
         versionCode flutterVersionCode.toInteger()