support non UTF-8 mingw filesystem

[magic-cucumber]

@JakeWharton close #1757.

• Refactored FileSystem.list(): Extracted the core logic into a variantList function.
  • Moved the original implementation to unixMain.
  • Replaced the implementation in mingwX64Main with wide-character Win32 APIs.
• Enhanced Error Reporting: Replaced FormatMessageA with FormatMessageW in lastErrorString to correctly handle wide-character error messages.
• Updated WindowsPosixVariant: Replaced all narrow-character function calls with their corresponding wide-character versions to ensure full compatibility with the Windows filesystem.

[magic-cucumber]

To test this PR, we need an Windows system with a non-UTF8 global encoding (such as GBK) and a test directory containing files with names that exceed the ANSI encoding range

[swankjesse]

This is neat!

[magic-cucumber]

I forget called spotlessApply..., but now it's all ok :D @swankjesse