Support load_geojson and load_url

[soxofaan]

spin off from #424 to properly track load_geojson/load_url support

(also related to Open-EO/openeo-python-driver#211 )

[soxofaan]

some todos for load_url:

openeo-python-client/openeo/rest/connection.py

Lines 1362 to 1366 in 5bb0da8

	if format not in self.list_input_formats():
	# TODO: make this an error?
	_log.warning(f"Format {format!r} not listed in back-end input formats")
	# TODO: Inspect format's gis_data_type to see if we need to load a VectorCube or classic raster DataCube
	return VectorCube.load_url(connection=self, url=url, format=format, options=options)

[soxofaan]

todos for load_geojson:

• support client side fetching from URL?
• unify some parts with DataCube._get_geometry_argument

openeo-python-client/openeo/rest/vectorcube.py

Lines 91 to 92 in 5bb0da8

	# TODO: unify with `DataCube._get_geometry_argument`
	# TODO #457 also support client side fetching of GeoJSON from URL?