Add extra chutney networks to Tor's CI

Let's add the following networks to Tor's chutney CI job:

• single-onion-v23 (or single-onion in 0.2.9)
• ipv6-exit-min (if we fix legacy/trac#30182 (moved), we should move the IPv6 exit check to macOS)

For speed, we can:

• skip basic-min
• replace hs-v2-min and hs-v3-min with hs-v23-min in 0.3.5 and later, and make the same change in:
  • make test-network
  • chutney Travis CI

IPv6 requires macOS in Travis:

• bridges+ipv6-min Depending on the version of tor in homebrew, which usually tracks stable:
• hs-v23-ipv6-md in 0.3.5 and later; hs-ipv6 in 0.2.9
• single-onion-v23-IPv6-md in 0.4.1 and later; single-onion-ipv6-md in 0.4.0 and 0.3.5; single-onion-ipv6 in 0.2.9