Adds CheckRequirements to base test class for extensions

Author: alex-kulakov

Extensions/TestCommon/CommonModelTest.cs

@@ -1,4 +1,8 @@
-using System.Collections.Generic;
+// Copyright (C) 2019-2020 Xtensive LLC.
+// This code is distributed under MIT license terms.
+// See the License.txt file in the project root for more information.
+
+using System.Collections.Generic;
 using NUnit.Framework;
 using TestCommon.Model;
 using Xtensive.Core;
@@ -55,5 +59,9 @@ protected virtual Domain BuildDomain(DomainConfiguration configuration)
     protected virtual void PopulateData()
     {
     }
+
+    protected virtual void CheckRequirements()
+    {
+    }
   }
 }