Bulk Windows fixes

[chiedo]

Why:

Shipping numerous work by @jeffmcaffer in bulk to avoid waiting for multiple checks.

This also enables windows tests on github/docs so we can run windows tests against branches here manually.

Closes #351
Closes #348
Closes #319
Closes #312
Closes: #137

Check off the following:

• All of the tests are passing.
• I have reviewed my changes in staging.
• For content changes, I have reviewed the localization checklist
• For content changes, I have reviewed the Content style guide for GitHub Docs.

[chiedo]

Tested it here on Windows by manually running the workflow: https://github.com/github/docs/runs/1233548947?check_suite_focus=true.

The only test that failed was a non-windows specific test on lint-ing so this is good to go!

[chiedo]

Closes #351 #348 #319 #312

[JamesMGreene]

Looks good. ✨

Thank you @jeffmcaffer and @chiedo! 💝

[github-actions]

Thanks very much for contributing! Your pull request has been merged 🎉 You should see your changes appear on the site in approximately 24 hours.

If you haven't already, you can add yourself to the list of contributors by creating a new comment in this PR using these instructions. Thanks again! ✨