Add Hippocorpus dataset script

[MightyAlex200]

This adds the Hippocorpus dataset script from #728 It's a notebook file which converts an existing Hippocorpus dataset into a Parquet file. This PR should stay a draft until the code quality and output quality is confirmed.

[github-actions[bot]]

:x: pre-commit failed. Please run pre-commit run --all-files locally and commit the changes. Find more information in the repository's CONTRIBUTING.md