Eng6647 updateclasses

ENG-6647: add a way to upsert new java classes to the catalog
ENG-6389: verify class loading and initializers during catalog update
ENG-6693: add a way to delete classes from the cluster's catalog

Small matching pull request in pro, just has an updated junit test.  All the meat is here.
Should addJarClassesToCatalog be mergeJarClassesToCatalog or upsertJarClassesToCatalog? Maybe that's dumb.