Packaging nixowo-icons

[davidak]

Can you add a Makefile like https://github.com/NixOS/nixos-artwork/blob/master/icons/Makefile, so we can package it like https://github.com/NixOS/nixpkgs/blob/nixos-22.05/pkgs/data/misc/nixos-artwork/icons.nix to replace nixos-icons?

I have quickly tested it here:

https://codeberg.org/davidak/nixos-config/src/commit/a2c4e696c83ad0800b67961627d250e5a955e30c/services/uwu-style.nix#L13-L17