[FIX] point_of_sale : Variant changing price

Current behavior:
When using variant in PoS the price was not always correct

Steps to reproduce:
1. Set up items with modifiers (Modifier type must be of type variant creation mode : never, where adding a modifier leads to a different price than with the base item e.g. base item is 10 USD, modifier is 5 USD, total price is 15 USD;
2. Activate Product configurator and make sure it's a Bar/Restaurant in the PoS settings
3. Select the items with the modifier;
4. Leave the table and come back to the table
5. Change the quantity of this product
6. The price is back to the base price without the modifier
opw-2696529

closes odoo/odoo#83444

X-original-commit: d959dfada11a72d6bc275b35f5eeb06b045a0dea
Signed-off-by: Masereel Pierre <pim@odoo.com>

addons/point_of_sale/models/pos_order.py

@@ -900,6 +900,7 @@ class PosOrderLine(models.Model):
         readonly=True, required=True)
     price_subtotal_incl = fields.Float(string='Subtotal', digits=0,
         readonly=True, required=True)
+    price_extra = fields.Float(string="Price extra")
     margin = fields.Monetary(string="Margin", compute='_compute_margin')
     margin_percent = fields.Float(string="Margin (%)", compute='_compute_margin', digits=(12, 4))
     total_cost = fields.Float(string='Total cost', digits='Product Price', readonly=True)
@@ -1029,6 +1030,7 @@ class PosOrderLine(models.Model):
             'pack_lot_ids': [[0, 0, lot] for lot in orderline.pack_lot_ids.export_for_ui()],
             'customer_note': orderline.customer_note,
             'refunded_qty': orderline.refunded_qty,
+            'price_extra': orderline.price_extra,
         }
 
     def export_for_ui(self):

addons/pos_restaurant/models/pos_order.py

@@ -61,6 +61,7 @@ class PosOrder(models.Model):
             'mp_dirty',
             'full_product_name',
             'customer_note',
+            'price_extra',
         ])
         return fields