Purchase - Add Products from BoM

On a purchase order form, a new button "Add Products from BoM" appears above the order lines. It opens a wizard where the user picks a finished product that has at least one Bill of Materials, chooses the BoM and a quantity, then clicks "Get Products from BoM". The wizard explodes the BoM and lists the raw components with their quantity to buy, unit of measure, purchase unit of measure, unit price, quantity available in stock, quantity after buy and total product value.

Each suggested line is selected by default; the user can unselect lines, change quantities or prices, and lines with no stock are highlighted in red. A component that itself has a BoM can be further exploded with "Add Products from BoM", and "Return Products from BoM" removes the lines created by that explosion. When the user clicks "Add Products", the selected components are added to the purchase order; if a component is already on the order, its quantity is increased instead of creating a duplicate line.

The module also adds a stored counter of Bills of Materials on products, used to filter the product selection. It touches purchase.order, purchase.order.line, product.product, mrp.bom and the two wizard models add.products.from.bom and add.products.from.bom.lines.