fix(AudioMuteButton): ensure track on unmute

If "startWithAudioMuted" option is used we need to make sure that new
local audio track will be created on unmute.

react/features/toolbox/components/AudioMuteButton.js

      */
     _setAudioMuted(audioMuted: boolean) {
         sendAnalytics(createToolbarEvent(AUDIO_MUTE, { enable: audioMuted }));
-        this.props.dispatch(setAudioMuted(audioMuted));
+        this.props.dispatch(setAudioMuted(audioMuted, /* ensureTrack */ true));
 
         // FIXME: The old conference logic as well as the shared video feature
         // still rely on this event being emitted.