[desktop-lite] Ability to use another Desktop Environment than Fluxbox

Hello everyone,

I'm currently writing a template that uses XFCE as the desktop environment instead of Fluxbox and I'd like to use the noVNC part of the desktop-lite module without having to install Fluxbox.

Any of the following methods would accomplish what I want :
- Split desktop-lite and noVNC into two separate features (either have the user use both or use `dependsOn` in desktop-lite)
- Ability to choose DE (time-consuming and can't be exhaustive)
- Ability to toggle off installation of Fluxbox

I do think splitting would be the best but it might be a hassle.