mgr/cephadm: add rados_id to nvmeof conf

mgr/cephadm: add rados_id to nvmeof conf

This is going to be used as the rados_id
to be set when connecting to the cluster using
the keyring we generate for the nvmeof daemon.

The python librados library defaults the name
to "client.admin" and so if we don't provide
a name or rados_id, we'll only be able to
use nvmeof with the "client.admin" keyring

Signed-off-by: Adam King <adking@redhat.com>