build: new build system

[nullishamy]

TODO:

• Assets
• Install helper May be integrated in the future if deemed required / someone contributes it
• Refactor build.py into a library No longer relevant, we will simply generate everything in CI
• Uninstall helper May be integrated in the future if deemed required / someone contributes it
• Add palette to patched colloid files (patches/colloid)
• Whatever this code does, if we need it?
  ^: We don't need the renaming anymore, we just handle that. Users will link with libadwaita themselves
• Cleanup dead code / refactor build.py

This completely reworks the build system. We are now sidestepping colloid's build system, and instead run a version of it re-implemented in python to suite our needs.

This changes the way we patch colloid too, now using git apply to apply patches to the submodule before building. We now properly integrate with colloid's palette system, eliminating the need to completely reset colloid's submodule at every run.

[nullishamy]

Can be reviewed from a code perspective, the theme itself is still being evaluated, and will be improved over time.