feat(external-api) Forward non participant message to iframe (#13440)

* Forward non-participant-message-received to iFrame API

* Updated comment

* Fix lint errors

conference.js

 
         room.on(
             JitsiConferenceEvents.NON_PARTICIPANT_MESSAGE_RECEIVED,
-            (...args) => APP.store.dispatch(nonParticipantMessageReceived(...args)));
+            (...args) => {
+                APP.store.dispatch(nonParticipantMessageReceived(...args));
+                APP.API.notifyNonParticipantMessageReceived(...args);
+            });
 
         room.on(
             JitsiConferenceEvents.LOCK_STATE_CHANGED,

modules/API/API.js

         });
     }
 
+    /**
+     * Notify external application (if API is enabled) if non participant message
+     * is received.
+     *
+     * @param {string} id - The resource id of the sender.
+     * @param {Object} json - The json carried by the message.
+     * @returns {void}
+     */
+    notifyNonParticipantMessageReceived(id, json) {
+        this._sendEvent({
+            name: 'non-participant-message-received',
+            id,
+            message: json
+        });
+    }
+
+
     /**
      * Notify the external application (if API is enabled) if the connection type changed.
      *

modules/API/external/external_api.js

     'mouse-enter': 'mouseEnter',
     'mouse-leave': 'mouseLeave',
     'mouse-move': 'mouseMove',
+    'non-participant-message-received': 'nonParticipantMessageReceived',
     'notification-triggered': 'notificationTriggered',
     'outgoing-message': 'outgoingMessage',
     'p2p-status-changed': 'p2pStatusChanged',