Check local sequential consistency in dbsim

- Release commit time critical section in callback
- Check the consistency inside commit order critical section

Other: Add 2pc switch to dbsim

dbsim/db_high_priority_service.hpp

@@ -69,6 +69,7 @@ namespace db
         high_priority_service& operator=(const high_priority_service&);
         db::server& server_;
         db::client& client_;
+        uint64_t commit_seqno_;
     };
 
     class replayer_service : public db::high_priority_service