Reimplement LinkML validation error categorization

[candleindark]

Reimplement how LinkML validation errors are categorized. The current implementation is based on a parsing of the error message

dandisets-linkml-status-tools/src/dandisets_linkml_status_tools/cli/tools.py

Lines 363 to 375 in 0b796dd

	def get_linkml_err_counts(errs: LinkmlValidationErrsType) -> Counter[str]:
	"""
	Get a `Counter` object that counts the LinkML validation errors by type
	:param errs: The list of LinkML validation errors to be counted
	:return: The `Counter` object
	Notes: The determination of the type of a LinkML validation error is rather
	rudimentary at this point.
	"""
	linkml_err_types = [
	re.sub(r".*(is .*) in \S.*", r"\1", e.message, count=1) for e in errs
	]
	return Counter(isorted(linkml_err_types))

Replace it with an implementation that is based on the validator and validator value made available by #13.