Add Socks6 support when/if the spec is ready

[essen]

There's currently a draft that has not been adopted yet by the intarea working group but that has some good progress. Worth keeping an eye on:

• https://datatracker.ietf.org/doc/draft-olteanu-intarea-socks-6/
• https://datatracker.ietf.org/wg/intarea/documents/