[Protocol v7] Remote unpublish & expose permissions (#101)

* fix

* impl

* oldPermissions

* mods

lib/src/core/signal_client.dart

@@ -170,6 +170,11 @@ class SignalClient extends Disposable with EventsEmittable<SignalEvent> {
           track: msg.trackPublished.track,
         ));
         break;
+      case lk_rtc.SignalResponse_Message.trackUnpublished:
+        events.emit(SignalTrackUnpublishedEvent(
+          trackSid: msg.trackUnpublished.trackSid,
+        ));
+        break;
       case lk_rtc.SignalResponse_Message.speakersChanged:
         events.emit(
             SignalSpeakersChangedEvent(speakers: msg.speakersChanged.speakers));