SCons: Extend MinGW support & checks

[Repiteo]

• Supersedes SCons: Fix MinGW tools on Windows native shells #91847

Extended logic for MinGW, primarily accounting for MSYS2/Cygwin not wanting to cooperate. Honestly, we might just want a blanket warning regarding MSYS2/Cygwin in the future; their MinGW implementations can be really troublesome. That aside, this PR also implements the explicit mingw Tool from SCons; consequently, there's now a means of natively generating res files, so the previous dedicated build function was removed

[akien-mga]

Code looks pretty clean to me, it's a nice improvement.

This logic is pretty brittle and there's a myriad of mingw distributions, so we need to make sure this is well tested:

• mingw-gcc on Linux
• mingw-gcc on macOS
• llvm-mingw on Windows, Linux, macOS
• MSYS2 on Windows
• scoop installed mingw on Windows
• more?

We might not need to test everything if a few are tested and work and the code logic itself seems sound.

CC @bruvzg

[bruvzg]

Changes looks fine.

Tested with:

• GCC on macOS (brew install)
• LLVM on macOS (standalone mstorsjo/llvm-mingw)
• GCC/MSYS2 on Windows
• GCC on Windows (scoop install)
• LLVM on Windows (standalone mstorsjo/llvm-mingw)

Linux MinGW installs depends on distro, but should more or less behave the same as on macOS.