Product Optional Product Quantity

This module replaces the standard optional products list on a product with a new editable list where each optional product also has a quantity. On the product form, the original optional products field is hidden and a new 'Optional Products Line' table appears instead, showing the optional product and its quantity.

Business rules enforced by the system: - A product cannot be added as an optional product of itself. - The same optional product cannot be added twice for the same product. - The quantity defaults to 1.

A new setting 'Optional Products Quantity' appears in the Sales settings area. When enabled, users in the 'Use Optional Products Quantity' group can see and edit the quantity column; other users do not see it. Salespeople can create, edit and delete optional product lines, while regular users can only read them.

The module also keeps the standard optional products field in sync automatically, so other parts of Odoo that rely on it continue to work. It touches the product template, the optional product line model, and the settings screen.