[Volunteer] Introduce JPA to Simplify Simple SQL and Reduce XML Files

### Volunteer help

Introduce the JPA framework to simplify some of the current simple SQL statements and reduce the number of XML files. Complex SQL statements can temporarily retain the use of XML.

The issue names no files, tests, or entry points, so first map the existing SQL and XML persistence configuration before choosing a JPA approach. Done means simple SQL statements use JPA, complex SQL may remain in XML temporarily, and the number of XML files is reduced.

Written by the indexing model from the issue text.