Switch to use the common library created for Eclipse Quarkus apps

In the past year, we have managed to get a common library live for Quarkus applications: https://gitlab.eclipse.org/eclipsefdn/webdev/eclipsefdn-api-common. This lib is for more complex projects, as for simple endpoints this is overkill. The common lib has packages for persistence and search built-in, so we should be able to leverage it pretty easily.

Most of the code in that package is based on features created in this repository, so it should be mostly 1 to 1. We are pretty busy with another project at the moment, but I can take some time in the next month to start this migration. It will greatly reduce the complexity of this project once implemented, and give us more stability/security through an upstream central project.