Coupons multi product criteria in sale

This module connects the multi-product criteria configuration with the sales coupon engine, so promotions defined with several product conditions can actually be applied on sale orders.

When Odoo evaluates which coupon programs apply to an order, it now also examines programs that use multi-product criteria. For each such program, every criterion must be satisfied by the products and quantities in the order (excluding reward lines). Depending on the "Repeat Product" setting, a criterion is met either by having at least one of the listed products with the minimum quantity, or by having one unit of every listed product.

• If the program applies on the current order and gives a product reward that is itself one of the criterion products, the reward quantity is subtracted before checking the minimum quantity.
• Programs whose criteria are not all met are removed from the list of applicable promotions.

It also adds read access to the multi-product criteria for salespeople and full access for sales managers, so they can view (and managers can configure) these criteria. The module touches coupon.program and the criteria model coupon_criteria_multi_product.model_coupon_criteria. No new menus or screens are added; the behaviour appears inside the existing coupon/promotion logic on sale orders.