Dataset controller, DataSet CRD v1

[MostAwesomeDude]

This PR adds a k8s CRD for datasets, as well as a controller which reads CRs, retrieves datasets from HF Hub, and uploads them to an OCI bucket.

This needs more work, but it's worth taking a quick look. Things I should do:

• Cache-invalidation logic, two-phase commit: should use a timestamp and a success flag to ensure that we never have partial uploads or double uploads
• Support splits besides "train"?
• More metrics