In order to achieve this, the parse_extended_hostname() had to be refactored
to return either success or failure and setting the hostname type in the given
parameter.

The reason for that is so it can detect invalid onion addresses that is having
a ".onion", the right length but just not passing validation.

That way, we can send back the prop304 ExtendedError "X'F1' Onion Service
Descriptor Is Invalid" to notify the SOCKS connection of the invalid onion
address.

Part of #30382

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