Update external tool for new label data in Ground Truth Labeler app
labelLoadListener( provides the
option to update the external tool that is connected to the Ground
Truth Labeler app when a new set of label data or new session with label data is
imported into the app. The app calls this method using the
object. Use this method to react to the event of loading a new label data into the app.
The client class can optionally implement this method.