Modernize search storage format for the MusicBrainz database

The MusicBrainz database has a Solr search engine used for both website search and search API. MB Search architecture for reference. After solr was upgraded to version 9, the schemas in configsets weren’t updated and still use version 1.5. They need to be upgraded to version 1.7. Solr currently keeps data in index fields for search and also uses _store field to store the index field data + other non index field’s data for response writer, causing redundancy. To eliminate this redundancy, we need to store all the required data in the fields themselves. Solr response writer currently reads all the data from _store field of a document and returns it in a valid MB XML/ MB JSON format. After modifying the configsets and indexer to store data in the fields, we need to create response writers that read from these fields and return data in a valid MB XML/ MB JSON format, along with validation tests for these writers. Since storing data in individual fields rather than a single _store blob will lead to change in performance,we will start with the artist core and benchmark it before rolling out to all remaining entities.