How do you create a folder like hierarchy when ingesting into Datahub, like the demo page does with prod > bigquery > bigquery-public-data? https://demo.datahubproject.io/browse/dataset/prod/bigquery/bigquery-public-data

This is called BrowsePath in DataHub. During ingestion through connectors the BrowsePath Aspect is sent. If you are using your own connector then you will have to send the aspect during ingestion. If you wish to make changes to browse paths sent by a connector for a dataset you can use a transformer https://datahubproject.io/docs/metadata-ingestion/transformers/