Display updated model version id

Some additional logging is needed when we successfully update an existing model version.

Add some logging on arkindex_worker.worker.training.TrainingMixin.update_model_version and arkindex_worker.worker.training.TrainingMixin.create_model_version to know the ID of the model version.

Please add some logger.info after the calls to CreateModelVersion and UpdateModelVersion upon completion to have a trace of the model version IDs involved.