Use a worker for file imports

arkindex/documents/fixtures/data.json

arkindex/documents/management/commands/bootstrap.py

arkindex/documents/management/commands/build_fixtures.py

arkindex/documents/tests/tasks/test_corpus_delete.py

arkindex/documents/tests/test_retrieve_elements.py

arkindex/process/builder.py

...ndex/process/management/commands/update_system_workers.py

arkindex/process/managers.py

...ndex/process/tests/commands/test_update_system_workers.py

arkindex/process/tests/test_create_process.py

arkindex/process/tests/test_create_s3_import.py

arkindex/process/tests/test_datafile_api.py

arkindex/process/tests/test_processes.py

arkindex/project/config.py

arkindex/project/settings.py

arkindex/project/tests/__init__.py

arkindex/project/tests/config_samples/defaults.yaml

arkindex/project/tests/config_samples/override.yaml

arkindex/project/tests/test_checks.py

arkindex/system_workers.yml