extracted crtp code to a separate class

utils/crtp.hpp

@@ -0,0 +1,18 @@
+#ifndef MEMGRAPH_UTILS_CRTP_HPP
+#define MEMGRAPH_UTILS_CRTP_HPP
+
+// a helper class for implementing static casting to a derived class using the
+// curiously recurring template pattern
+
+template <class Derived>
+class Crtp
+{
+public:
+
+    Derived& derived()
+    {
+        return *static_cast<Derived*>(this);
+    }
+};
+
+#endif