[ADD] product_customer_code_picking module v.7.0

Moving the MP: https://code.launchpad.net/~agilebg/stock-logistic-flows/adding_product_customer_code_picking/+merge/202472
@gdgellatly actually the involved views are ```stock.view_move_picking_tree``` and ```stock.view_move_picking_form``` that are used within the picking form only.
This is why we did not make the field stored