Allow to define picking location for inventory moves of customer shipment
To allow wave picking #4909, we need to be able to set the storage location from where the customer shipments must pick the products.
This location will not store for the long term the product and so it will be most of the time empty. This location will be filled by the internal order points to create the picking wave (internal shipment).
So I propose to add a new field on warehouse 'picking_location' with a 'child_of' domain of 'storage_location'.