feat(jaas) add config for displaying participants stats and conference subject

config.js

     // otherwise the app doesn't render it.
     // moderatedRoomServiceUrl: 'https://moderated.jitsi-meet.example.com',
 
+    // Hides the conference subject
+    // hideConferenceSubject: true
+
     // Hides the conference timer.
     // hideConferenceTimer: true,
 
+    // Hides the participants stats
+    // hideParticipantsStats: true
+
     // Sets the conference subject
     // subject: 'Conference Subject',
 

react/features/base/config/configWhitelist.js

     'forceTurnRelay',
     'gatherStats',
     'googleApiApplicationClientID',
+    'hideConferenceSubject',
+    'hideParticipantsStats',
     'hideConferenceTimer',
     'hiddenDomain',
     'hideLobbyButton',

react/features/conference/components/native/NavigationBar.js

  * @returns {Props}
  */
 function _mapStateToProps(state) {
+    const { hideConferenceTimer, hideConferenceSubject } = state['features/base/config'];
+
     return {
         _conferenceTimerEnabled:
-            getFeatureFlag(state, CONFERENCE_TIMER_ENABLED, true) && !state['features/base/config'].hideConferenceTimer,
+            getFeatureFlag(state, CONFERENCE_TIMER_ENABLED, true) && !hideConferenceTimer,
         _meetingName: getConferenceName(state),
-        _meetingNameEnabled: getFeatureFlag(state, MEETING_NAME_ENABLED, true),
+        _meetingNameEnabled:
+            getFeatureFlag(state, MEETING_NAME_ENABLED, true) && !hideConferenceSubject,
         _visible: isToolboxVisible(state)
     };
 }

react/features/conference/components/web/Subject.js

      */
     _showParticipantCount: boolean,
 
+    /**
+     * Whether the conference subject should be shown or not.
+     */
+    _showSubject: boolean,
+
     /**
      * The subject or the of the conference.
      * Falls back to conference name.
      * @returns {ReactElement}
      */
     render() {
-        const { _hideConferenceTimer, _showParticipantCount, _subject, _visible } = this.props;
+        const { _hideConferenceTimer, _showParticipantCount, _showSubject, _subject, _visible } = this.props;
 
         return (
             <div className = { `subject ${_visible ? 'visible' : ''}` }>
-                <span className = 'subject-text'>{ _subject }</span>
+                { _showSubject && <span className = 'subject-text'>{ _subject }</span>}
                 { _showParticipantCount && <ParticipantsCount /> }
                 { !_hideConferenceTimer && <ConferenceTimer /> }
             </div>
  * @returns {{
  *     _hideConferenceTimer: boolean,
  *     _showParticipantCount: boolean,
+ *     _showSubject: boolean,
  *     _subject: string,
  *     _visible: boolean
  * }}
  */
 function _mapStateToProps(state) {
     const participantCount = getParticipantCount(state);
+    const { hideConferenceTimer, hideConferenceSubject, hideParticipantsStats } = state['features/base/config'];
 
     return {
-        _hideConferenceTimer: Boolean(state['features/base/config'].hideConferenceTimer),
-        _showParticipantCount: participantCount > 2,
+        _hideConferenceTimer: Boolean(hideConferenceTimer),
+        _showParticipantCount: participantCount > 2 && !hideParticipantsStats,
+        _showSubject: !hideConferenceSubject,
         _subject: getConferenceName(state),
         _visible: isToolboxVisible(state) && participantCount > 1
     };