Migrate to Jakarta JSON API

Starting with JEE 9 the package names for the enterprise APIs changed from javax.* to jakarta.* which means that we will benefit from updates to those APIs only if we make the move.

For the feature model and the related tooling, it should be fairly easy to do this move as this code is usually only used at tool time but not at application runtime.

We can simply replace javax.json with jakarta.json and do new releases of everything involved with a new major version. As we are currently using javax.json in parts of the API, this will be a breaking change, therefore the major version update.