This function outsources Cinder's encryption passphrase handling based
on Key Manager secrets. It extends Cinder's existing implementation to
handle secret objects of type 'passphrase' additionally, for which the
binascii.hexlify conversion is now skipped similar to Nova's
implementation of handling qcow2+LUKS images. Original Cinder behavior
for 'symmetric' secret objects is retained.
Provides the basis for image encryption standardization as per
https://specs.openstack.org/openstack/cinder-specs/specs/2024.2/LUKS-image-encryption.html
Co-Authored-By: Josephine Seifert <josephine.seifert@cloudandheat.com>
Change-Id: I8836fe3c2af5b61ba33a7fe3c8eb5a7f4961c515
2b42257eff