Also write CSS and assets to xdg-config/gtk-4.0
The GTK4 version of Breeze doesn't inherit color scheme at all without this.
Thought I would see if I could squeeze this in before Plasma 5.26 feature freeze. I don't think that the way I'm iterating between the two GTK versions is particularly idiomatic, but it does work. Please feel free to tell me if there's another way you would rather I do it. @teams/qa