3274a286cc
Lots of newer apps that use their appid as their icon name don't set window icons, since they aren't used in GNOME. Instead of setting it manually in every app, just default to it. Only set the icon if it exists in the icon theme. Remove manually set default icons in the demo. No tests as GtkApplication doesn't have any in the first place. Fixes https://gitlab.gnome.org/GNOME/gtk/-/issues/7120