feat: add log message after writing a field

src/data_handler/data_logger.cpp

@@ -38,6 +38,7 @@ void DataLogger::handle(Collection& collection, const chrono::DateTime& timestep
     if (handler_) {
         handler_->handle(collection, timestep_begin, timestep_end);
     }
+    os_ << "Finished writing : " << collection.name() << std::endl;
 }
 
 } // namespace yaco