- Added new `django-viewflow` and `django-filter` dependencies to `requirements.txt`.
- New file `viewflow.py` under `/audit/models/` which contains the FSM logic for transitioning an SAC.
- Moved `STATUS` enumeration outside of the `SingleAuditChecklist` class. This required import/reference changes across many files and tests.
- Removed references of old deprecated library `django-fsm`.
- New migration to handle the changing the SAC's `submission_name` field to remove dependency on the deprecated `django-fsm`.