Initialize rbd pool at pool creation

Initialize rbd pool at pool creation

When creating a RBD pool it needs to be initialized as per documentation[1]
Modified (pre_)generate_ceph_cmd to make it usable with any command with
the same parameters as the ceph command

[1]https://docs.ceph.com/en/latest/rbd/rados-rbd-cmds/#create-a-block-device-pool

Signed-off-by: Teoman ONAY <tonay@redhat.com>
(cherry picked from commit c39bbc3deaf7a02d36daa39d752e91e94afb3c3e)