New table and service to store auth tokens

Implements the auth token retrieval and storage for the identity implementation. This is now automatically done for providers and the back office user manager can be used to retreive and store all tokens.

Fixes locking on the config writer.

Removes the abstract NodeObjectTypeId from the base repo since it shouldn't be there.

src/Umbraco.Infrastructure/Persistence/Repositories/Implement/DictionaryRepository.cs

@@ -1,4 +1,4 @@
-using System;
+using System;
 using System.Collections.Generic;
 using System.Linq;
 using Microsoft.Extensions.Logging;
@@ -120,11 +120,6 @@ namespace Umbraco.Cms.Infrastructure.Persistence.Repositories.Implement
             return new List<string>();
         }
 
-        protected override Guid NodeObjectTypeId
-        {
-            get { throw new NotImplementedException(); }
-        }
-
         #endregion
 
         #region Unit of Work Implementation