Specifically `homix`
- remove manual `home-manager` module definition
Import `(r)agenix` and `agenix-rekey` by default for all `NixOS` configurations
Move `machines.nix` flake module import to `configuration.nix` from `flake.nix`
Pass around `perSystem`'s `pkgs` instances to the system configurations
Some more refactoring in `configurations`' `mkHost` functions
Also start using `home-manager`'s `useGlobalPkgs` option
Also use `mkShellNoCC` for default `devShell`
Also `nix flake update`