[jpa] Add dynamic import, upgrade dependencies, add UI config (#13516)

[jpa] Add dynamic import, upgrade dependencies, add UI config (#13516)

* Adds a dynamic package import so JDBC drivers on the classpath can be used
* Upgrades OpenJPA from 2.4.0 to 3.2.2
* Upgrades Derby JDBC driver from 10.11.1.1 to 10.16.1.1
* Adds config.xml and ConfigurableService annotation so add-on can be configured using the UI
* Adds null annotations on all classes
* Prevent NPEs and some code cleanup

See also:

* https://openjpa.apache.org/builds/3.2.2/apache-openjpa/RELEASE-NOTES.html
* https://community.openhab.org/t/jpa-with-mysql-or-mariadb/138679

Fixes #13375

Signed-off-by: Wouter Born <github@maindrain.net>