relay: New file relay_resolve_addr.{c|h}

This commit moves router_pick_published_address() and the related helper
functions into the new file.

The log_addr_has_changed() function has been made public in router.h so we can
use it in relay_resolve_addr.c.

This is a refactoring as part of Sponsor 55. Only code movement at this
commit.

Part of #33789

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

src/test/test_config.c

@@ -42,6 +42,7 @@
 #include "core/or/policies.h"
 #include "feature/rend/rendclient.h"
 #include "feature/rend/rendservice.h"
+#include "feature/relay/relay_resolve_addr.h"
 #include "feature/relay/router.h"
 #include "feature/relay/routermode.h"
 #include "feature/nodelist/dirlist.h"