async onAppReady(event) {
    Object.assign(this.context, {
      isAppReady: true,
    });
  }
Hook that is called after app sends ready signal
over the web socket.

@protected
@async
@param {Object} event - App ready event object
@param {string} event.deviceId - Current deviceId
@param {string} event.bundleId - Current bundleId
@param {number} event.pid - Process id of the running app
@return {Promise<void>} - when done