Drop JDO usage and support and replace by native JCR - warning: custom workflow extensions breakage

With this issue all JDO (datanucleus) usage will be removed from Hippo CMS (all modules) and replaced by native JCR calls.
This will primarily impact the Repository (Document and Workflow API) but also will need adjustments from the CMS and all modules pulling in or defining jdo/datanucleus dependencies.

For custom Workflow extensions extending org.hippoecm.repository.api.WorkflowImpl and/or org.hippoecm.repository.api.ext.Document this might require code changes.