gtk4: init at 4.0.2

Major API change; adds multimedia and 3D graphics widgets.

Changes:
- https://gitlab.gnome.org/GNOME/gtk/-/blob/4.0.2/NEWS
- https://blog.gtk.org/2020/12/16/gtk-4-0/

Co-authored-by: Jan Tojnar <jtojnar@gmail.com>
Co-authored-by: Tad Fisher <tadfisher@gmail.com>

pkgs/development/libraries/gtk/hooks/gtk4-clean-immodules-cache.sh

@@ -0,0 +1,11 @@
+# shellcheck shell=bash
+
+fixupOutputHooks+=(_gtk4CleanComments)
+
+# Clean comments that link to generator of the file
+_gtk4CleanComments() {
+    local f="${prefix:?}/lib/gtk-4.0/4.0.0/immodules.cache"
+    if [ -f "$f" ]; then
+        sed 's|Created by .*bin/gtk-query-|Created by bin/gtk-query-|' -i "$f"
+    fi
+}