Log address discovered by the directory authorities

It would be interesting to log the discovered address when it's by the directory authorities.

mentioned in merge request !223 (closed)

assigned to @guinness

mentioned in issue #40206 (closed)

mentioned in merge request !244 (merged)

Hey I took over this one since we ought to get this in 045 asap and holidays are coming. Thus, closing MR !233 (closed) in favor of the new one !244 (merged).

Thanks @guinness

closed with commit aae9a05a