cephadm: Set ms bind ipv6 when mon-ip is ipv6

cephadm: Set ms bind ipv6 when mon-ip is ipv6

If you use cephadm bootstrap with an ipv6 mon ip then currently you'll
get into a address family split-brain state, where the mon's messenger
connects and binds to ipv6 but the mgr's binds to ipv4 (usually
0.0.0.0). In this state the bootstrap process hangs as it attempts to
talk and get the mgr state.

A work around is to have `ms bind ipv6 = true` in a ceph conf
you can then pass to bootstrap which gets pulled in and set in mon's
config store.

This patch sets `ms bind ipv6 = true` to the global section in the
mon config store when the mon-ip argument is an ipv6 address.

Fixes: https://tracker.ceph.com/issues/45016
Signed-off-by: Matthew Oliver <moliver@suse.com>