iddata refactoring

[matthewcornell]

implementation of design4.md

• updated to latest iddata commit hash
• also need to review: "Regenerated all three NSSP expected CSVs (state, hsa, both) using the current code with the same mocks, since the old CSVs were generated against the pre-refactor load_data() API whose NSSP data differed from the new NSSPDataSource."