feat: Move Dataset Repository into ELI5

What does this merge request do and why?

Migrating data form datasets into ELI5.

This is all data and schemas, as well as any new documentation or required documentation updates.

How to set up and validate locally

Numbered steps to set up and validate the change are strongly suggested.

Merge request checklist

• Tests added for new functionality. If not, please raise an issue to follow up.
• Documentation added/updated, if needed.

closes gitlab-org/modelops/ai-model-validation-and-research/ai-evaluation/prompt-library#517 (closed)