Change datahub-ingester to index hub resources only

[CathyJinJNCC]

We no longer want the hub asset pages to show up in the search (unless they have no resources) so we need to strip out the hub "parent" asset page logic. However, we still want people to have access to the metadata on the asset page so change the resource URLs to point to the hub page with an anchor to the resource link. See wireframes and document diagram in epic for reference.

• Remove logic for indexing asset pages with resources. Asset pages without resources are still indexed however.
• Change logic for indexing resources to not include redundant parent_id, parent_title, and parent_resource fields
• Change url in resource document to point to the hub page with the resource link as the anchor (only if it is a data.jncc.gov.uk file resource). e.g. https://hub.jncc.gov.uk/assets/99690728-aafd-4b44-ab22-31847e2184bc#Chile-Viticulture-mapping-layers.zip. URL resources (e.g. pointing to web resources or files not hosted by us) point back to the asset page.
• Add an asset_id field to allow all documents for an asset to be queried and deleted for reindexing/republishing