feat(events): include JitsiTrack as an argument of TRACK_MUTE_CHANGED

modules/RTC/JitsiLocalTrack.js

             return self._sendMuteStatus(mute);
         })
         .then(function() {
-            self.eventEmitter.emit(JitsiTrackEvents.TRACK_MUTE_CHANGED);
+            self.eventEmitter.emit(JitsiTrackEvents.TRACK_MUTE_CHANGED, this);
         });
 };
 

modules/RTC/JitsiRemoteTrack.js

         this.stream.muted = value;
 
     this.muted = value;
-    this.eventEmitter.emit(JitsiTrackEvents.TRACK_MUTE_CHANGED);
+    this.eventEmitter.emit(JitsiTrackEvents.TRACK_MUTE_CHANGED, this);
 };
 
 /**