All the tests pass. I tried to keep as much as possible the same, but a
few things don't translate well to Caddy 2, notably one test in
probe_resist_test.go on L200, I had to change that test case since I
didn't quite understand why it was the way it was before.
Does not yet have v2 Caddyfile support.
Make it look closer to standard Transport.DialTLS, because it's good to be
like standard things.
This also allows usage of thrid party TLS stacks, enabling
https://github.com/refraction-networking/utls.Roller integration.