mgr/cephadm: support Ceph client object cache settings for NFS

Add NFS service-spec options to configure Ganesha CEPH FSAL client
object caching.

Spec fields:
  enable_client_object_cache
  client_object_cache_size
  client_object_cache_max_dirty

When set, these are written into a CEPH block in ganesha.conf as
client_oc / client_oc_size / client_oc_max_dirty. They are also added
to NFS deps so changing them triggers a daemon redeploy.

Fixes: https://tracker.ceph.com/issues/78296
Signed-off-by: Shweta Bhosale <Shweta.Bhosale1@ibm.com>