extensionsService: Fix copying technical details when extension crashes
This was forgotten when porting to GTK 4, leading to the following error when user tries to copy the error message produced by an extension:
JS ERROR: TypeError: Gtk.Clipboard is undefined
_initActions/<@resource:///org/gnome/Shell/Extensions/js/extensionsService.js:255:31
run@resource:///org/gnome/Shell/Extensions/js/dbusService.js:177:20
main@resource:///org/gnome/Shell/Extensions/js/main.js:19:13
run@resource:///org/gnome/gjs/modules/script/package.js:206:19
start@resource:///org/gnome/gjs/modules/script/package.js:190:8
@/nix/store/fwnkwvhwm3kqck4fhkc5y5z853radggg-gnome-shell-40.0/share/gnome-shell/.org.gnome.Shell.Extensions-wrapped:7:17