show vector feature properties in layerswitcher

vector data may include additional properties next to the actual geometry for each feature. those properties shall be listed in the layer switcher component, e.g. via a table.

example feature with additional properties:

{"type": "FeatureCollection", "features": [{"id": "0", "type": "Feature", "properties": {"end_node": 411744478, "start_node": 210645487, "travel_time": 9330.2}, "geometry": {"type": "MultiLineString", "coordinates": [[[12.1580199, 52.4036749], ...]]]}}]}

resulting table in the layer switcher:

id	end_node	start_node	travel_time	geometry
0	411744478	210645487	9330.2	MultiLineString

the table will contain as many entries as there are features in the vector layer.