Windows support

[fwal]

Adds support for windows runners.

• Resolve correct version
• Download Swift package
• Setup Swift on windows
• GPG signature validation
• Tests

Fixes #132.

Help wanted!

As I have limited experience from and access to a windows environment I could benefit from additional help.
Currently I'm trying to figure out how to run commands in the "VS2019 Command Prompt" as required by the toolchain.
Any help in this area would be greatly appreciated!

[Zialus]

Some Relevant information here

[doozMen]

I made a test on windows and I thing we should wait unfortunately swift ton windows does not yet support spm. But I would be glad to help. Keep up the good work!

[fwal]

Hi @doozMen!

Yeah it also seems like the installer requires the use of a GUI which is a no-go on CI but hopefully this will change soon.

Thanks for trying!

[compnerd]

@fwal it shouldn't. I've been using the installer on GH Actions for a while now with automated installations: https://github.com/compnerd/swift-win32/blob/main/.github/workflows/windows.yml

[fwal]

@compnerd That's great news and thank you for the example action, that helps a lot! 🎉

[MaxDesiatov]

I wonder if there's an easy way to call into PowerShell from TypeScript in the code action, or to make it composite only on Windows? I've created a separate action specifically for Windows, and I wonder if your action could maybe use mine as a step somehow? https://github.com/MaxDesiatov/swift-windows-action

[fwal]

Closed in favour of #424 🎉