container: root: common: add interpreter exit function

Wrapper (with optional message) to underlying interpreter exit call.

container/src/root/common/utility.hh

@@ -276,6 +276,19 @@ int exec(const std::string& cmd)
   return gSystem->Exec(cmd.c_str());
 }
 
+//! \brief Exit the interpreter with given status (and message)
+//! \param code Exit code status (return code)
+//! \param message Optional exit message
+//! \since docker-finance 1.2.0
+void exit(const int code, const std::string& message = {})
+{
+  // TODO(unassigned): logger
+  if (!message.empty())
+    std::cout << "Exiting: '" << message << "'" << std::endl;
+
+  gSystem->Exit(code);
+}
+
 //! \brief Make current timestamp
 //! \return timestamp in "yyyy-mm-ddThh:mm:ssZ" format
 //! \since docker-finance 1.0.0