Integrate the bootstrapper into this project

[ChipWolf]

Hey folks,

I wanted to propose simplifying the packwiz-installer setup by integrating the bootstrapper directly into the this repo. The idea is to combine everything into a single packwiz-installer.jar that handles updates natively, while still building the bootstrap jar as a separate artifact for backwards compatibility.

How it could work:

• The main packwiz-installer.jar would handle updates itself.
  • It would check for updates, download a new binary if needed, and launch a bootstrap process to replace the running binary and restart.
  • This bootstrap process would be split off into a temporary directory to avoid issues with file locks.
• The standalone bootstrap jar would still be built as a separate artifact, so workflows relying on it wouldn’t break.

I think this is worth doing as it simplifies things—most users get a single jar that just works, CI for pack testing etc. is less fiddly with fewer artifacts, and we still keep the current binaries available for anyone who wants it.

Let me know what you think—I can share code or examples if needed! 🚀

Cheers!