feat(remote_mute): Add analytics event

JitsiConferenceEventManager.js

@@ -72,6 +72,8 @@ JitsiConferenceEventManager.prototype.setupChatRoomListeners = function() {
 
     chatRoom.addListener(XMPPEvents.AUDIO_MUTED_BY_FOCUS,
         value => {
+            Statistics.analytics.sendEvent('conference.remotelyMuted');
+
             // set isMutedByFocus when setAudioMute Promise ends
             conference.rtc.setAudioMute(value).then(
                 () => {