Swamy/remove unused usings and reorganize usings (#489)

* Removed and Reordered the using statements

* Removed and Reordered the usings inside Web Project

* Removed and Reordered the usings inside PublicApi project

* Removed Unused usings and reorganized usings inside Infrastructure project

src/Web/Views/Manage/ManageNavPages.cs

@@ -1,6 +1,6 @@
-using System;
-using Microsoft.AspNetCore.Mvc.Rendering;
+using Microsoft.AspNetCore.Mvc.Rendering;
 using Microsoft.AspNetCore.Mvc.ViewFeatures;
+using System;
 
 namespace Microsoft.eShopWeb.Web.Views.Manage
 {