ceph: check for kv engine version for SSE RGW
ceph: check for kv engine version for SSE RGW

The "https://docs.ceph.com/en/latest/radosgw/vault/" says RGW supports only version v2 of
kv engine, so pod won't start if the admin didn't provide "VAULT_BACKEND" in security.kms.ConnectionDetails

Signed-off-by: Jiffin Tony Thottan <ac134a614b50f2e879db85acb9f4b45b24a210dc@gmail.com>

rook/rook,rook/nfs,rook/rook,rook/rook,rook/nfs,rook/rook,rook/nfs,rook/rook