nfs: add a new common/admin/nfs subpackage
nfs: add a new common/admin/nfs subpackage

This will provide APIs for managing NFS exports via the Ceph NFS manager
module.

Signed-off-by: John Mulligan <eda8ad33169deab44f9fe65847f99e368da6c91b@redhat.com>

ceph/go-ceph,ceph/go-ceph,ceph/go-ceph