wrapGAppsHook: add package’s own modules to GIO_EXTRA_MODULES

When a package provides both executables and gio modules, it is quite
probable the executables will need those modules. wrapGAppsHook wraps
executables with GIO_EXTRA_MODULES picked up from dependencies
but forgets about the package being built. Let’s add to consideration.

Closes: https://github.com/NixOS/nixpkgs/issues/50254