Fix - legacy catalog items versioning

* Correctly load java classes from the catalog (legacy mechanism), taking into account versioning precedence.
* Tag the resulting entities with the catalogItemId used for loading.
* Fix the catalog link in rest response.
* Fix the UI link to catalog items for applications.
Should we move this into `usage/rest` somewhere? Or if left here then is there a better name that indicates it relates to a URI path? No strong feelings.