[RM-6990] Attributes of the same hdf5 dataset can come from different OperatorResults

Created on 2022-01-20 13:38:38 by Ali Allaoui. % Done: 0

Related to #6683 (if we want to put first pass results in model_parameters dataset)
When ResultStoreOutput is populated, it supposes that every attribute of a dataset come from the same operatorResult, therefore it retrieves the operator result only once by dataset, and also use a caching mechanism (the dict ResultStoreOutput.operator_results populated in get_operator_result )