Match muted behavior with JS SDK (#32)

* attempt 1

* implement

* clean up

* clean up

* cleaner code

* mute was opposite

* fix suggestion

* fix local pub muted

* update example

* update pubs

* format

lib/src/participant/participant.dart

@@ -1,5 +1,4 @@
 import 'package:collection/collection.dart';
-import 'package:livekit_client/src/track/track.dart';
 import 'package:meta/meta.dart';
 
 import '../events.dart';
@@ -8,6 +7,7 @@ import '../logger.dart';
 import '../managers/event.dart';
 import '../proto/livekit_models.pb.dart' as lk_models;
 import '../support/disposable.dart';
+import '../track/track.dart';
 import '../track/track_publication.dart';
 import '../types.dart';
 import 'remote_participant.dart';
@@ -199,6 +199,11 @@ extension ParticipantTrackSourceExt on Participant {
         true);
   }
 
+  bool isScreenShareEnabled() {
+    return !(getTrackPublicationBySource(TrackSource.screenShareVideo)?.muted ??
+        true);
+  }
+
   /// Find a track publication by its [TrackSource]
   TrackPublication? getTrackPublicationBySource(TrackSource source) {
     if (source == TrackSource.unknown) return null;