This changes a LOT of code but in the end, behavior is the same.
Unfortunately, many functions had to be changed to accomodate but in majority
of cases, to become simpler.

Functions are also removed specifically those that were there to convert an
IPv4 as a host format to a tor_addr_t. Those are not needed anymore.

The IPv4 address field has been standardized to "ipv4_addr", the ORPort to
"ipv4_orport" (currently IPv6 uses ipv6_orport) and DirPort to "ipv4_dirport".

This is related to Sponsor 55 work that adds IPv6 support for relays and this
work is needed in order to have a common interface between IPv4 and IPv6.

Closes #40043.
Signed-off-by: David Goulet <dgoulet@torproject.org>

Part of 33222.

Add an address family argument to the functions that launch relay ORPort
self-test circuits.

Part of 33222.

If a file doesn't use the file command (either \file or @file),
Doxygen won't try to process it.

(It turns out that some of the functions in router.h didn't even
exist any more, so I just got to delete their declarations completely.)