feat(face-landmarks) add API event for providing face landmark data (#11347)

modules/API/API.js

         });
     }
 
+    /**
+     * Notify external application (if API is enabled) that some face landmark data is available.
+     *
+     * @param {Object | undefined} faceBox - Detected face(s) bounding box (left, right, width).
+     * @param {string} faceExpression - Detected face expression.
+     * @returns {void}
+     */
+    notifyFaceLandmarkDetected(faceBox: Object, faceExpression: string) {
+        this._sendEvent({
+            name: 'face-landmark-detected',
+            faceBox,
+            faceExpression
+        });
+    }
+
     /**
      * Notify external application (if API is enabled) that the list of sharing participants changed.
      *

modules/API/external/external_api.js

     'email-change': 'emailChange',
     'error-occurred': 'errorOccurred',
     'endpoint-text-message-received': 'endpointTextMessageReceived',
+    'face-landmark-detected': 'faceLandmarkDetected',
     'feedback-submitted': 'feedbackSubmitted',
     'feedback-prompt-displayed': 'feedbackPromptDisplayed',
     'filmstrip-display-changed': 'filmstripDisplayChanged',

react/features/face-landmarks/actions.js

 } from './functions';
 import logger from './logger';
 
+declare var APP: Object;
+
 /**
  * Object containing  a image capture of the local track.
  */
                     id: localParticipant.id
                 });
             }
+
+            APP.API.notifyFaceLandmarkDetected(faceBox, faceExpression);
         };
 
         const { faceLandmarks } = getState()['features/base/config'];