Module presets

E.g. 

- `desktop`, to enable utilities only needed on my machines
- `cluster`, for shared ones
- `gnome`, for the specific GUI DE, but also assuming some tools

All of them will enable some other configurations (e.g. `gnome` will toggle `dconf` and graphical utilities, while `tex` is only needed on specific machines, so it should never be toggled - or even exposed only as a dedicated shell).