[FIX] pos_restaurant: Print date on Bill Receipt before Payment

Steps to reproduce :
- Open a pos_restaurant session with Print Bill before Payment selected
- Add some products
- Print a Bill before Payment

Bug :
The receipt does not show the order date

Fix :
After that commit, the receipt shows the order date

Explanation :
The field date.localestring (that appears in the Order Receipt) is computed in the point_of_sale module for
the receipt after payment (in Payment Screen) but was not computed in the pos_restaurant for the receipt before payment

closes odoo/odoo#108235

Signed-off-by: Trinh Jacky (trj) <trj@odoo.com>

addons/pos_restaurant/static/src/js/Screens/ProductScreen/ControlButtons/PrintBillButton.js

@@ -14,6 +14,7 @@ odoo.define('pos_restaurant.PrintBillButton', function(require) {
         async onClick() {
             const order = this.env.pos.get_order();
             if (order.get_orderlines().length > 0) {
+                order.initialize_validation_date();
                 await this.showTempScreen('BillScreen');
             } else {
                 await this.showPopup('ErrorPopup', {