rbd-mirror: Allow to copy the admin keyring
rbd-mirror: Allow to copy the admin keyring

The ceph-rbd-mirror role allows to copy the admin keyring via the
copy_admin_key variable but there's actually no task in that role
doing the job.

Signed-off-by: Dimitri Savineau <a50a620e679eed14f4e99998b821cea8884cf228@redhat.com>

ceph/ceph-ansible,ceph/ceph-ansible