types: Add Controller Metadata and Namespace Metadata

types: Add Controller Metadata and Namespace Metadata

Port and extent the libnvme part from the commit "Add NVMe MI
Features: Controller Metadata (0x7E) and Namespace Metadata (0x7F)."
from the nvme-cli monolithic branch.

While at it add the missing definitions and add some documentation.

This is based on Tokunori Ikegami first port attempt.

Signed-off-by: Daniel Wagner <dwagner@suse.de>