test_nfs4_acls: Add test for mapping CREATOR entries to NFS4 ACL entries

test_nfs4_acls: Add test for mapping CREATOR entries to NFS4 ACL entries

Add testcase for mapping DACL entries CREATOR OWNER and CREATOR GROUP
with inheritance flag in the security descriptor to NFSv4 "special
owner" and "special group" entries. This is the correct mapping for
these entries as inheriting "special owner" and "special group" grants
permissions to the actual owner and owning group of the new file or
directory, similar to what CREATOR entries do.

The other side is that CREATOR entries without any inheritance flags do
not make sense, so these are not mapped to NFSv4 ACL entries.

BUG: https://bugzilla.samba.org/show_bug.cgi?id=14032

Signed-off-by: Christof Schmitt <cs@samba.org>
Reviewed-by: Ralph Boehme <slow@samba.org>