DBMS now returns a unique pointer to a GraphDbAccessor

Summary: See above.

Reviewers: mislav.bradac

Reviewed By: mislav.bradac

Subscribers: pullbot

Differential Revision: https://phabricator.memgraph.io/D120

tests/integration/query_engine_common.hpp

@@ -139,7 +139,7 @@ auto ExecuteQueryPlans(Logger &log, QueryEngineT &engine, Dbms &dbms,
     // Create new db_accessor since one query is associated with one
     // transaction.
     auto db_accessor = dbms.active();
-    engine.Run(query, db_accessor, stream);
+    engine.Run(query, *db_accessor, stream);
   }
 }