feat(medusa, admin-ui): Improve gift card application (#4944)

Fix for the problems identified in issue #4892 

Bugfix: admin-ui order summary no longer uses gift card total from order when displaying how much has been withdrawn from each giftcard.

Bugfix(?): no longer keep applying gift cards (at 0 value) when sufficient balance has been reached

Feature: multiple giftcards are now applied in ordered fashion. First by end_date (supports null), then by remaining balance. In order to ensure that customers ends up with as long lasting and few remaining gift cards as possible after the transaction.

integration-tests/factories/simple-gift-card-factory.ts

@@ -9,6 +9,7 @@ export type GiftCardFactoryData = {
   value: number
   balance: number
   tax_rate?: number
+  ends_at?: Date
 }
 
 export const simpleGiftCardFactory = async (
@@ -29,6 +30,7 @@ export const simpleGiftCardFactory = async (
     value: data.value,
     balance: data.balance,
     tax_rate: data.tax_rate,
+    ends_at: data.ends_at
   })
 
   return await manager.save(toSave)