[llvm] [workflows] Port buildkite Windows config to GitHub actions (PR #82093)

[Vlad Serebrennikov via llvm-commits]

Endilll wrote:

> Please point me to the "multiple times" where this has been detailed, I think I followed the discussion, yet I don't know what you mean.

Tom pointed out to this almost two weeks ago in https://discourse.llvm.org/t/rfc-future-of-windows-pre-commit-ci/76840/4
> We chose these projects for testing on the release branch, because at the time, these were the most the we could build without running into the disk space limitations or the 6 hour build timeout.

Back then you also [suggested](https://discourse.llvm.org/t/rfc-future-of-windows-pre-commit-ci/76840/20?u=endill) that we can "just enable" all projects, and I agreed, as long as we "don’t spend another two weeks on this". Here we are today, with Windows CI completely disabled, and you still pushing against at least some kind of replacement.

https://github.com/llvm/llvm-project/pull/82093