Migrate to jakarta json

The cm.json module is currently using javax.json in its API as well as in its implementation.
We should migrate this code to use the (newer) jakarta.json API instead.
However, as javax.json is currently used in the API, this will be a breaking change to all downstream users.
Therefore we should make it possible to run the old and the new implementation in parallel (including as a library) and also make sure that we support / maintain the old implementation as needed.