Adds an intent handler for incoming Intents. If there are pending Intents when the listener is added, only the last Intent raised will be received.
Example
const contextHandler = (context) => {
myViewChartListener(context);
};
const listener = fdc3.addIntentListener('ViewChart', contextHandler);
function myAppCloseSequence() {
// to unsubscribe the handler, simply call:
listener.unsubscribe();
}