19105 Use Drupal entity API for harvest_runs table, with refactor

[paul-m]

• Creates an entity called harvest_run. This entity has the following features:
  • Various UUID-oriented fields from the JSON data blob are normalized into the following base fields with unlimited cardinality:
    • extracted_uuid
    • load_new_uuid
    • load_updated_uuid
    • load_unchanged_uuid
    • orphan_uuid
  • This allows for instance doing a normalized query to find which run created which dataset, etc.
  • Data not stored in entity base fields remains in the JSON blob, which is written to a column called data.
• Many calls to HarvestService::getAllHarvestRunInfo() only need the IDs, so add HarvestService::getAllHarvestRunIds() so we can just do an entity query for IDs without the overhead of loading entities or parsing JSON.
• Do entity conversion on update.
• Add HarvestRunRepository for ease of calling between HarvestService and HarvestRun entity methods.
• Some refactor of harvest Drush commands
• Update HarvestService to use new run repo.
• Update HarvestUtility for the new run repo.
• Update tests to use run entity/repo.

[dafeder]

I think we have a winner