Implement raw-dylib for Windows

[bjorn3]

This will require generating import libraries using the object crate. I don't know what the exact format of import libraries is, but I do know that MSVC and MinGW use an incompatible format.

[bjorn3]

Rust 1.71.0 released which stabilizes this feature, so it might become high priority to implement this in the near future if windows-sys switches to it.

[bjorn3]

rust-lang/ar_archive_writer#15 has ported LLVM's import library writer to rust. Using it from cg_clif produces identical import libraries as cg_llvm. It isn't enough however as we also need to match cg_llvm in when to use __imp_ dllimport symbols, which we currently never use.

[bjorn3]

Implemented in #1524.