Add click event listener to markers

[paodb]

Similar to

GoogleMapsAddon/src/main/java/com/flowingcode/vaadin/addons/googlemaps/GoogleMapPolygon.java

Line 154 in 5c03f95

public static class GoogleMapPolygonClickEvent extends ClickEvent<GoogleMapPolygon> {

but for markers with DomEvent = google-map-marker-click.