Short description of changes

• Move all autobuild/windows/* scripts to a single autobuild/windows.ps1 script which is called for the different stages (setup/build/get-artifacts).
• Condense redundant parameter parsing into a single step
• Simplify jack build naming
• Create functions with proper names for larger steps
• Inline Github artifact output definition as it's shorter that way
• Make coding style more consistent (spaces, curly braces)

CHANGELOG: Autobuild: Refactored and simplified Windows build scripts.
(will be condensed...)

Notes:

• This is a rather large Diff which cannot be easily followed. I'm sorry for that, but I don't see any way to make this better. I'm usually a fan of having individual commits for sub-changes, but in this case it would have required artificially creating "bad" intermediate states just to fix them in a later commit. Therefore, the diff is rather large, but I'm hoping that the resulting file is way more readable than what we had before.
• I've kept the script in autobuild/ as it used to be. We can also think of moving all autobuild scripts (now that they are only a single script) to their platform folder, e.g. move autobuild/windows.ps1 to windows/autobuild.ps1. If wanted, I can do this as part of this PR.
• This PR drops some error checking code which is not relevant for Github-initiated builds as it makes the scripts way shorter and more readable. They error checks sound like they may have been relevant during development or when running locally. However, the scripts were not designed to run locally as they make use of the Github-setup build environments and techniques (e.g. magic set-output lines; it's not impossible, but it wasn't straight-forward either; it's still possible and might be a bit more straight-forward at least).
• Doing this for Windows is obviously just the first step. After this PR, the other platforms will be a bit unaligned in how the scripts are run. I still chose to submit this now because I consider it ready and I think it's easier to review and reason about. PRs for the other platforms will be done in the coming days (even if I was unable to manage to complete them timely for whatever reasons, all platforms are in working state).
• Once all platforms are converted to the new model, I'll simplify the build matrix (it will be enough to supply a single base command: entry for each platform). I will also drop a number of unneeded commands (GITHUB_WORKSPACE extra logic).

Context: Fixes an issue?

#2282 (reply in thread)
Related: #2503

Does this change need documentation? What needs to be documented and how?

No.

Status of this Pull Request

What is missing until this pull request can be merged?

• Artifact size should be compared. Result: Artifacts from this PR match the size of artifacts from latest master run
• It should be confirmed that the JACK binary does in fact use JACK and not ASIO

Checklist

• I've verified that this Pull Request follows the general code principles
• I tested my code and it does what I want
• My code follows the style guide
• I waited some time after this Pull Request was opened and all GitHub checks completed without errors.
• I've filled all the content above