test_nfs4_acls: Add test for mapping from NFS4 to DACL CREATOR entries
Add testcase for mapping from NFSv4 ACL entries for "special owner" and
"special group" to DACL entries in the security descriptor. Each NFSv4
entry here with INHERIT_ONLY maps directly to a CREATOR OWNER or CREATOR
GROUP entry in the DACL. Entries without INHERIT_ONLY map to the CREATOR
entry and an additional explicit entry granting permission on the
current object.