Add chat categorization dataset

[hinthornw]

This task is meant to test a couple things:

1. Classification -> both on common things where it is expected to perform well (e.g., sentiment, toxicity -> which currently is always 0)
2. Structured json output -> the schema is nested, which confused some of the smaller 7b models i tested out but works fine for llama 32b code instruct (and OAI/anthropic)

Includes a couple common things like enums.

TODO: Clean up notebooks and add more analysis