Remove use of IFD #33
Description
https://nixcademy.com/posts/what-is-ifd-ups-and-downs/
- Generate zig <-> nix, nix <-> toolchain mappings
- Store additional build.zig.zon metadata in the zon2json-lock / generated nix file
IFD causes flake check to fail, and generally IFD is frowned upon.
This means fromZON will go away eventually.