addContextMenuListener does not work for LTileLayer or LWmsLayer

[basisbit]

It seems like addContextMenuListener does not work for map image layers. The LeafletContextMenuListener.onContextMenu are never executed when you right-click on the map-tiles.

For many use cases, just adding a LeafletContextMenuListener to the LMap does not deliver the desired results. For example any contextclicks above widgets will also be handled by that listener and even show the LMap as event source. Thus it would be nice to be able to add LeafletContextMenuListener to image tile layers.