mgr/cephadm: convert host addr if non-IP to IP

mgr/cephadm: convert host addr if non-IP to IP

Previously we allowed the host.addr to be a DNS name (short or fqdn).
This is problematic because of the inconsistent way that docker and podman
handle /etc/hosts, and undesirable because relying on external DNS is
an external source of failure for the cluster without any benefit in
return (simply updating DNS is not sufficient to make ceph behave).

So: update any non-IP to an IP as soon as we start up (presumably on
upgrade).  If we get a loopback address (127.0.0.1 or 127.0.1.1), then
wait and hope that the next instance of the manager has better luck.

Signed-off-by: Sage Weil <sage@newdream.net>
(cherry picked from commit 781bfa14ffc9aa37eb85635a59af1f202999e874)