feat: emit raise hand event to external API (#8312)

* Expose raise hand event to external application

* Fix linting issues

* fix the app non existing issue

react/features/base/participants/middleware.js

@@ -448,6 +448,10 @@ function _raiseHandUpdated({ dispatch, getState }, conference, participantId, ne
         raisedHand
     }));
 
+    if (typeof APP !== 'undefined') {
+        APP.API.notifyRaiseHandUpdated(participantId, raisedHand);
+    }
+
     if (raisedHand) {
         dispatch(showNotification({
             titleArguments: {