docs: Handle gi-docgen namespaces when looking for types to link
docs: Handle gi-docgen namespaces when looking for types to link

Otherwise causes issue when looking for GtkApplication and you end up with a GApplication link

gtk-rs/gir,GuillaumeGomez/gir,gtk-rs/gir,GuillaumeGomez/gir,gtk-rs/gir,GuillaumeGomez/gir