DRCDP facets need to be supported for search

[sashakames]

Example query:

https://esgf-node.ornl.gov/esgf-1-5-bridge?project=DRCDP&offset=0&limit=10&type=Dataset&format=application%2Fsolr%2Bjson&facets=downscaling_source_id%2C+institution_id%2C+driving_source_id%2C+driving_experiment_id%2C+source_id%2C+version_realization%2C+variable_id%2C+driving_activity_id%2C+data_node&latest=true&query=*&downscaling_source_id=MIROC6

The facets that were added for DRCDP:

- region_id
- downscaling_source_id
- driving_activity_id
- driving_experiment_id
- driving_source_id    
- domain_id
- driving_institution_id
- driving_variant_label
- domain

The facet counts seem to work but using a facet in the query string returns an error response