libnvdimm/labels: Add claim class helpers

libnvdimm/labels: Add claim class helpers

In preparation for LIBNVDIMM to manage labels on CXL devices deploy
helpers that abstract the label type from the implementation. The CXL
label format is mostly similar to the EFI label format with concepts /
fields added, like dynamic region creation and label type guids, and
other concepts removed like BLK-mode and interleave-set-cookie ids.

CXL labels do have the concept of a claim class represented by an
"abstraction" identifier. It turns out both label implementations use
the same ids, but EFI encodes them as GUIDs and CXL labels encode them
as UUIDs. For now abstract out the claim class such that the UUID vs
GUID distinction can later be hidden in the helper.

Reviewed-by: Jonathan Cameron <Jonathan.Cameron@huawei.com>
Link: https://lore.kernel.org/r/162982116719.1124374.9917866609080940364.stgit@dwillia2-desk3.amr.corp.intel.com
Signed-off-by: Dan Williams <dan.j.williams@intel.com>