CI should confirm that the `test_data` is up to date with the latest live horde

[tazlin]

The CI relies on the files in tests/test_data to accurately perform its function.

• I could switch to generating this data on the fly always but I think this would introduce other kinds of non-obvious behavior which might be more confusing in the long run. Moreover, relying exclusively on remote data could be problematic for a variety of reasons.
• At a minimum, I think a separate workflow job should validate if the test_data matches what would be generated by the scripts. This would allow PRs which do not necessarily require that the test_data be updated still run through CI while still highlighting the fact that there are still fields or objects on the API unknown to the SDK.