Loads iterations generated by .create_iterations that were created in a
previous session. If these are not available, this is indicated by setting a
return flag.
.load_iterations(file_dir, iteration_file = NULL)List containing:
iteration_file_exists: An indicator whether an iteration file was found.
iteration_list: The list of iterations (if available).
project_id: The unique project identifier (if available).
Path to directory where iteration files are stored.