update the code by following the review suggestions.

Oqtane.Shared/Enums/ViewMode.cs

@@ -1,14 +0,0 @@
-using System;
-using System.Collections.Generic;
-using System.Linq;
-using System.Text;
-using System.Threading.Tasks;
-
-namespace Oqtane.Enums
-{
-    public enum ViewMode
-    {
-        View,
-        Edit
-    }
-}

Oqtane.Shared/Models/UserSetting.cs

@@ -8,8 +8,6 @@ namespace Oqtane.Models
 {
     public class UserSetting
     {
-        public const string ViewMode = "Page:ViewMode";
-
-        public const string LastViewPage = "LastViewed";
+        public const string LastViewPageId = "Page:LastViewed";
     }
 }