Add support for system-level config in /etc/xdg/wluma/

[jirutka]

[max-baz]

Thanks! I learn a lot from you, somehow I didn't know about /etc/xdg at all until now...

I think to do this right we should properly support $XDG_CONFIG_DIRS, the current library doesn't support it, but there is another one which we perhaps should just switch to, which for example has this neat helper:

https://github.com/whitequark/rust-xdg/blob/1e2020a763e6b30d6bf9f4a69ab68d008a937f59/src/lib.rs#L405-L408

Let me know if you want to do it, otherwise I'll do it myself.

[boredland]

Hi there! I'd be very interested in this change, so we could ship a vendor config with manjaro sway. Sadly I am a bit out of my league regarding rust - any way I could help getting this functionality shipped?

[max-baz]

Implemented in #66 🙂 👍