Allow stock transfer orders to include "Stock items" that don't have "Products"

Following the completion of Stock transfer between sites/contract brewers/offsite packagers on delivery schedule (Stock Movement Documents) I’ve adjusted this thread to be for specifically the option to transfer stock items that don’t have products set up as the work done for the other project has otherwise covered this.

I’ll also merge another thread below, which equates to the same request to keep all the votes in one place.