Refactor to eliminate unneeded BasketQueryService

src/ApplicationCore/Entities/BasketAggregate/Basket.cs

@@ -10,6 +10,9 @@ public class Basket : BaseEntity, IAggregateRoot
     private readonly List<BasketItem> _items = new List<BasketItem>();
     public IReadOnlyCollection<BasketItem> Items => _items.AsReadOnly();
 
+    public int TotalItems => _items.Sum(i => i.Quantity);
+
+
     public Basket(string buyerId)
     {
         BuyerId = buyerId;

src/ApplicationCore/Interfaces/IBasketQueryService.cs

@@ -1,8 +0,0 @@
-using System.Threading.Tasks;
-
-namespace Microsoft.eShopWeb.ApplicationCore.Interfaces;
-
-public interface IBasketQueryService
-{
-    Task<int> CountTotalBasketItems(string username);
-}