Change FolderStructure and other file handling to support a single-iteration ECS transformation and data load project structure

Right now, the only viable way to manage an ECS migration is to create multiple "iteration" folders for the same iteration (one for each tenant in the ECS system). It should be possible to process an ECS iteration from one iteration folder.

Design thoughts:
* Results files should include the relevant ecs_tenant_id for their task (from the task_configuration)
* This includes all *_id_map and related files (eg. bound with mappings)
* Log files should include tenant information in the file name and in the logs, themselves, including "friendly" names from mod-consortia
* Perhaps ecs_tenant_id-specific directories under the main results and reports directories?