Work out which networks to run in Chutney's CI

Work out which networks to run, and if they should have separate jobs.

We don't need to test all the networks, just the ones that test chutney features. In particular, we don't need a tor version vs chutney network matrix: that should go in the tor branch CI, not the chutney CI.

The default network should test as many of tor/chutney's features as possible. If this network breaks on a particular tor version, we look at that Tor version's CI to see which particular networks have broken.

Then we want a separate job for each separate feature:

• a bridge network from "make test-network-all"
• an onion service v2 and v3 network from "make test-network-all"
• an IPv6 network from "make test-network-all"

We can add other networks as needed:

• when we add new features to chutney, like PTs
• if we break existing features without breaking chutney's CI
• if we break tor's CI without breaking chutney's CI