Add missing catalog tests

[rambleraptor]

Rationale for this change

There's a couple missing catalog tests around supporting namespaces + tables with slashes/dots. Along the way, I found an issue in how we create the CreateTableRequest + RegisterTableRequest

Are these changes tested?

Tests are included.

Are there any user-facing changes?

[kevinjqliu]

should we just add namespace_exists to all the catalog implementations?
similar to the one in the rest catalog,

iceberg-python/pyiceberg/catalog/rest/__init__.py

Lines 1106 to 1131 in 2f293d6

	@retry(**_RETRY_ARGS)
	def namespace_exists(self, namespace: str | Identifier) -> bool:
	namespace_tuple = self._check_valid_namespace_identifier(namespace)
	namespace = self._encode_namespace_path(namespace_tuple)
	# fallback in order to work with older rest catalog implementations
	if Capability.V1_NAMESPACE_EXISTS not in self._supported_endpoints:
	try:
	self.load_namespace_properties(namespace_tuple)
	return True
	except NoSuchNamespaceError:
	return False
	response = self._session.head(self.url(Endpoints.namespace_exists, namespace=namespace))
	if response.status_code == 404:
	return False
	elif response.status_code in (200, 204):
	return True
	try:
	response.raise_for_status()
	except HTTPError as exc:
	_handle_non_200_response(exc, {})
	return False

[rambleraptor]

Yeah, I agree 100% with this. I created #2969. I can make a separate PR, but I feel like it'll potentially muddy this one to add it here. How does that sound?

[kevinjqliu]

do you know why theres a behavior difference here?
ideally we're testing for consistent catalog behaviors in this class

[rambleraptor]

I didn't think of this as an actual issue, but maybe it is.

Calling list namespaces would get you:

rest_catalog - new
others - new.db

That's because iceberg-rest-fixture treats this as hierarchical namespaces, which many other catalogs don't support. The spec supports hierarchical namespaces, so that seems to be working as intended.

My comment was very poor, so I wrote an actual comment to explain this.

[jayceslesar]

Nice!