eliminate `rdflib.term.Genid` and `rdflib.term.RDFLibGenid`

[aucampia]

I don't think there is any situation in which RDFLib will create instances of these classes (after #1821 is merged) and it is not clear why they exist. I think it would be best to remove them entirely.

rdflib/rdflib/term.py

Lines 358 to 389 in 57f993d

	class Genid(URIRef):
	__slots__ = ()
	@staticmethod
	def _is_external_skolem(uri: Any) -> bool:
	if not isinstance(uri, str):
	uri = str(uri)
	parsed_uri = urlparse(uri)
	gen_id = parsed_uri.path.rfind(skolem_genid)
	if gen_id != 0:
	return False
	return True
	class RDFLibGenid(Genid):
	__slots__ = ()
	@staticmethod
	def _is_rdflib_skolem(uri: Any) -> bool:
	if not isinstance(uri, str):
	uri = str(uri)
	parsed_uri = urlparse(uri)
	if (
	parsed_uri.params != ""
	or parsed_uri.query != ""
	or parsed_uri.fragment != ""
	):
	return False
	gen_id = parsed_uri.path.rfind(rdflib_skolem_genid)
	if gen_id != 0:
	return False
	return True