sync: add new repositories for vault & settings

Notesnook.API/Models/SyncItem.cs

@@ -110,6 +110,9 @@ namespace Notesnook.API.Models
         } = Algorithms.Default;
     }
 
+    [MessagePack.MessagePackObject]
+    public class SettingItem : SyncItem { }
+
     [MessagePack.MessagePackObject]
     public class Attachment : SyncItem { }
 
@@ -139,4 +142,7 @@ namespace Notesnook.API.Models
 
     [MessagePack.MessagePackObject]
     public class Color : SyncItem { }
+
+    [MessagePack.MessagePackObject]
+    public class Vault : SyncItem { }
 }