replace counter by specific query to avoid load each items in memory (#611)

* replace counter by specific query to avoid load each items in memory

* Create IBasketQueryService

src/ApplicationCore/Interfaces/IBasketQueryService.cs

@@ -0,0 +1,9 @@
+using System.Threading.Tasks;
+
+namespace Microsoft.eShopWeb.ApplicationCore.Interfaces
+{
+    public interface IBasketQueryService
+    {
+        Task<int> CountTotalBasketItems(string username);
+    }
+}

src/ApplicationCore/Interfaces/IOrderRepository.cs

@@ -1,11 +0,0 @@
-using Microsoft.eShopWeb.ApplicationCore.Entities.OrderAggregate;
-using System.Threading.Tasks;
-
-namespace Microsoft.eShopWeb.ApplicationCore.Interfaces
-{
-
-    //public interface IOrderRepository : IAsyncRepository<Order>
-    //{
-    //    Task<Order> GetByIdWithItemsAsync(int id);
-    //}
-}