Fix GNU toolchain compatibility with direct object linking (Continuation of #11)

[kkua]

🚀 Summary

This PR is a continuation of the work started by @arihant2math in #11. It adds support for multiple executables and fixes the GNU toolchain compatibility issues reported by the maintainer.

🛠️ Changes & Fixes

I have rebased the original changes onto the latest main branch and applied the following fixes:

1. Fixed GNU Toolchain Compatibility (Solution from Rust 1.61 in Linux does no add resources to the EXE mxre/winres#40)

   Inspired by the solution proposed by @rodrigorc in , instead of relying on --whole-archive (which is not supported by x86_64-w64-mingw32-gcc), we now pass the object file path directly via cargo:rustc-link-args.
   println!("cargo:rustc-link-args={}", output.display());

This forces the linker to unconditionally include the object file in the EXE, without needing --whole-archive.

🤝 Credits

• The core logic for multi-executable support was implemented by @arihant2math (PR Add multi executable support #11).
• The GNU toolchain fix is based on Solution n.2 proposed by @rodrigorc in .