The options API has been updated, in order for a more flexible setup
with `local.modules.desktop.enable` being replaced with an enum of
desktops at `local.systemVars.desktop`, which allows for switching
desktop environments by changing a single option. This is so that we can
switch to cosmic and only enable the programs we need (i.e. disable
greetd because we use cosmic-greeter and enable terminals since that is
desktop related). This is simpler than having a different module per
desktop.
