Add support for nix-darwin to talon-nix

[ProfDoof]

Goal

Wanted to add support for nix-darwin to talon-nix so that I could share my talon set-up easily between my machines.

Changes

• I switched from nixpkgs to nixpkgs-unfree to allow for the use of legacyPackages and prevent adding more instances of nixpkgs to any users.
• Used an enum in the scraper to allow for adding other options later if that's ever possible. Might be something to consider using to allow for beta combined with some allowances from talonvoice.
• Made modules each into their own file to prevent setting udev rules for Mac while breaking common code out into a file
• Changed to using a json.dump on the file instead of manually writing it to the file
• Made the packages handle the respective cases for Linux and Darwin
• Added a folder for the various build derivations and added the build derivations for linux and darwin to it

[ProfDoof]

@Mic92 myself and others have several PRs in this repo but not had any responses from the maintainers.

[Mic92]

I contacted adisbladis to figure out what the status of maintenance is.

[ProfDoof]

@Mic92 have you heard back from adisbladis

[Mic92]

I don't think he ever responded. But I also no longer no on which channel I asked.