mgr/cephadm: add a module option for controlling cephadm log dest

mgr/cephadm: add a module option for controlling cephadm log dest

Now that cephadm has multiple possible persistent logging destinations
we need a way to choose which one to use when the command is started by
the mgr. Add the option 'cephadm_log_destination' which can take one
of 'file', 'syslog', or 'file,syslog'. If left unset (empty string)
then the behavior is equivalent to 'file' and that is the same as
previous cephadm versions.

Fixes: https://tracker.ceph.com/issues/62233
Signed-off-by: John Mulligan <jmulligan@redhat.com>