feat (tfa): some improvements

• Generalize the logging to avoid repeating " [{trans_id}], this must implies to create a new class containing execute_transformation_check and the associated methods, where trans_id will be a class attribute
• After files have been "reassigned", if they are still failed jobs, send a mail/report on those jobs only with the associated files.
• Send a mail when transformation is set to completed
• Check that the tasks status update is really done by the "WorkflowTaskAgent". If yes remove the "update tasks status" method.
• Can we treat the "parent" transformations before the child
• How to manage stalled jobs ?