Alpha test more quietly

[petemounce]

Fixes #629.

Checklist

• make test-all (UNIX) passes. CI will also test this
• unit and/or integration tests are included (if applicable)
• documentation is changed or added (if applicable)

Description of change

[aelsabbahy]

What's this failure all about? ss command not found on windows?

[petemounce]

Yeah, ss doesn't appear to exist on Windows, so the command falls back to a random port selection. :(

I didn't find a similarly-fast way on Windows to find a randomly selected available port.

• netstat -an too slow, tens of seconds
• sysinternals tcpvcon -ac fast, doesn't include port like the GUI variant tcpview does 🤦

So, I wrote a piece of powershell and included it into this PR - hope the change is ok within this PR, but if not, happy to slice it to a different one? f01f093

[petemounce]

I enjoyed cb7c137.