feat(home-manager): allow enabling GTK, cursors and icons separately

[PerchunPak]

GTK port is deprecated and will be soon removed (see catppuccin/gtk#262). And I wanted a way to use cattpuccin cursors without risking breaking my configuration during update in the near future.

[getchoo]

part of this is actually being done in #195 already - namely separating the cursors from the main gtk module to avoid this warning. icons are sort of separated in this as well, but i did plan on making a follow up PR to separate them in a similar way to the cursors. if you'd like, you could re-use some of the work here to a new catppuccin.gtk.iconTheme option similar to this in a new PR

in any case, thank you so much for this work! as it seems we came to basically the same conclusion, i know it probably took you a good bit. sorry i have to close this :(

[PerchunPak]

i know it probably took you a good bit. sorry i have to close this :(

Don't worry, this PR took me literally 10 minutes, it is not a problem at all

I don't like Papirus icons, so don't worry about doing duplicate work again ;)