Replace getsockname with tor_getsockname
There's a lot of duplicate code in Tor that calls getsockname, then stuffs the address in a tor_addr_t.
Let's cleanup that code by replacing it with tor_getsockname where that makes sense.
For example, in #18100 (moved), we left behind duplicate code in destination_from_socket, because it was a backport, and the changes required to deduplicate it were complex.