Properties that take in GTypes should also be able to take in a GObject.Object

[vixalien]

Given the following scenario:

const data_model = new Gio.ListStore({ item_type: Book });

/*
Property '__type__' is missing in type 'typeof Book' but required in type 'GType<unknown>'.ts(2741)
gobject-2.0.d.ts(23, 13): '__type__' is declared here.
gio-2.0.d.ts(33512, 17): The expected type comes from property 'item_type' which is declared here on type 'Partial<ConstructorProps<Object>>'
*/

I think it should be safe that parameters that accept GTypes should also take in GObjects as GJS will automatically get the Object's gtype.