feat(external_api): Add method for displaying participant on large video

modules/API/API.js

         },
         'set-large-video-participant': participantId => {
             logger.debug('Set large video participant command received');
-            sendAnalytics(createApiEvent('largevideo.participant.changed'));
+            sendAnalytics(createApiEvent('largevideo.participant.set'));
             APP.store.dispatch(selectParticipantInLargeVideo(participantId));
         },
         'subject': subject => {

modules/API/external/external_api.js

         return setAudioOutputDevice(this._transport, label, deviceId);
     }
 
+    /**
+     * Displays the given participant on the large video. If no participant id is specified,
+     * dominant and pinned speakers will be taken into consideration while selecting the
+     * the large video participant.
+     *
+     * @param {string} participantId - Jid of the participant to be displayed on the large video.
+     * @returns {void}
+     */
+    setLargeVideoParticipant(participantId) {
+        this.executeCommand('setLargeVideoParticipant', participantId);
+    }
+
     /**
      * Sets the video input device to the one with the label or id that is
      * passed.