feat: fold purchase and promo voucher fields into one code field

src/Form/Service/CreateFieldStateProvider.php

@@ -332,11 +332,11 @@ class CreateFieldStateProvider extends AbstractFieldStateProvider
         // Vouchers cannot be redeemed or submitted for inquiry bookings
         $finalBookingOnlyCondition = new FinalBookingOnlyCondition();
 
-        $this->fieldStateConditions['purchaseVoucherCode'] = [
+        $this->fieldStateConditions['voucherCode'] = [
             'hidden' => CompositeCondition::not($finalBookingOnlyCondition),
         ];
 
-        $this->fieldStateConditions['promoVoucherCode'] = [
+        $this->fieldStateConditions['removeVoucherCode'] = [
             'hidden' => CompositeCondition::not($finalBookingOnlyCondition),
         ];