CI: run .NET Framework Integration Tests on Windows

[mus65]

This runs the .NET Framework tests on Windows by setting up WSL2 in the Windows VM with Vampire/setup-wsl and starting the SSH server container with podman in the Ubuntu VM. This should catch more Windows specific issues than the current mono solution does.

To my surprise, this actually works. It's pretty slow though. A full test run takes about an hour. Also the already flaky test from #1253 has failed on every run so far. I assume the bad performance is somehow due to the nested virtualization.

We could either disable the flaky test and live with the long CI time or only test specific tests here, like before with mono. Or not do this at all since it still feels a little experimental...

Why not with docker? Docker Desktop is not supported on Windows Server. Setting up docker in the ubuntu VM manually is a lot more complex than podman since it must be run as a daemon. I tried this as well, but couldn't get it to work. It can't connect to the Ubuntu VM for some reason.

[Rob-Hague]

Awesome. I also tried to setup docker with WSL2 but decided I didn't know enough about it and gave up

[Rob-Hague]

Could it be separated into a third leg, such that the publish step does not depend on its success? And then we can see how it goes with reliability

Some of the slowness might be because a lot of the tests make several connections between test initialise and cleanup. For example, the tests in CipherTests each make 6 connections. But it doesn't seem to be that costly locally so perhaps not worth optimising

[Rob-Hague]

Have you normally only seen that particular test fail or others as well? If it's just that one, then I think we can disable it in CI (would like to keep it locally - I'm pretty sure it's a bug)

[mus65]

I have only seen this particular test fail. I skip it now by checking for the CI env variable. There may be a better skip the test. NUnit has an [Explicit] attribute for this, but seems like MSTest doesn't have anything similar.