messages_ctdb: Add messaging_ctdb_connection

messages_ctdb: Add messaging_ctdb_connection

This will be the replacement for messaging_ctdbd_connection(). This does not
default to initializing messaging but panics. We just don't have correct
default arguments for messaging_init. Implicit multiple messaging and event
contexts is a bug also.

It *might* be that some tools fail due to this, but this needs fixing in
different ways. See the previous commit for smbpasswd.

Signed-off-by: Volker Lendecke <vl@samba.org>
Reviewed-by: Ralph Boehme <slow@samba.org>