* .github/workflows/windows.yml: Add support for Visual Studio 2022

This is available in github actions since some time now [1].

[1]: https://github.com/actions/virtual-environments/issues/3949

* README.md: Add VS 2022 [skip ci]

The version and the build engine version (aka MSBuild version) were
taken from [1].

[1]: https://github.com/actions/virtual-environments/blob/win22/20220116.1/images/win/Windows2022-Readme.md