Also run tests on Windows Server 2022 GitHub Runner

[TBBle]

Low-hanging fruit, but nice to have in place while things like #1160 are in-flight.

Outstanding thoughts:

• Make this a matrix job? Is it worth it for the two versions we care about until the mid-2020's?
• While I'm on the topic, we probably should either test or explicitly declaim Server 2016 support. The README currently points to a system requirements doc that includes Server 2016... this solves itself in less than 4 months anyway.

[dcantah]

Somehow the CI is still showing a "test" check that is "Waiting for status to be reported" 😐

[TBBle]

Weird. I wonder if that's because there's a test job in the mainline, and it doesn't like the idea of me removing tests like that. It's not 'CI / test' as it is without my change, for that matter.

I wonder if a matrix job would be better or be just as confusing for it.

[TBBle]

Drat. The matrix job was pretty easy (and gives a better diff, and more DRY), but it's still showing a mysterious 'test' job as required.

For that matter, I'm not sure what actually makes a particular step 'Required' here, but if that's actually a repository configuration rather than in .github/workflows/ci.yml (i.e. the same way DCO and license/cla are hooked up), then that would explain why test is appearing here even without such a job present in the YAML.

Edit: Poking around, it's probably a repository setting, the master branch will be set to "Require status checks to pass before merging", and it has the 'test' status check listed there. I suspect that list hasn't been updated as other CI stages have been added either, as I assume it currently lists "lint", "build", test", and "license/cla".

Edit again: Yeah, that's it, I can see the protections in the GitHub API.

> curl -H "Accept: application/vnd.github.v3+json" https://github.com/gitapi/repos/Microsoft/hcsshim/branches/master
...
  "protected": true,
  "protection": {
    "enabled": true,
    "required_status_checks": {
      "enforcement_level": "non_admins",
      "contexts": [
        "license/cla",
        "build",
        "lint",
        "test"
      ]
    }
  },
  "protection_url": "https://github.com/gitapi/repos/microsoft/hcsshim/branches/master/protection"
}

So trivially changing test to test (windows-2019) and test (windows-2022) would fix this (the settings UI lets you search in recent test run names). Or removing 'test' at least. It might be worth marking DCO as required too, and perhaps some of the other stages.

[anmaxvl]

looks like we'd have to remove test from required checks, merge this PR and update the settings again? We could also use our administrator powers to merge this PR regardless the status of checks. what do you think @microsoft/containerplat ?

[TBBle]

I could also add a test job that runs the Windows 2019 tests again, then we merge this, then change the GitHub config, and then a new MR that removes the (now-duplicate) test job. That feels pretty yucky though, and needlessly churny.

If I was making the decision, I'd force-accept this, and then change the GitHub config. We can see that the new test jobs have passed, after all. Although other PRs in-flight would then need to be rebased to pass the new checks, or similarly force-merged.

The ideal would be if GitHub could be told "test or test (windows-2019) is required", but I don't think it's that sophisticated.