Merging recent developments in jet grooming

@delsart, I put together the new JetTrimming class you prepared with my JetGroomer, making the former a subclass of the latter. I think this way it ends up being quite neat, as for any given grooming method, one just has to define the per-jet operation, and configure a filter with the appropriate setup in initialize(). In fact even most of the per-jet operation is the same, it's only the decorations that need to be changed -- so in principle we could even think of moving even more into the JetGroomer class.

In the process, I also reworked PseudoJetTranslator to eliminate bare pointers -- we can work with references everywhere to make the memory management a mite more robust.

A few other minor changes:

• Created a WriteHandleKey for the output pseudojets in JetGroomer and JetClusterer -- I think it is better to communicate this explicitly to the scheduler. This is autoconfigured, so initialize will print a warning if the user sets any value. Lastly, I changed the name of the container to be ToolName+"FinalPJ", because I think this will be more unique (I think the previous setup could clash if you had 2 jet collections built from the same merged PJ container).
• Merging the various Read/WriteHandles, I thought UngroomedJets and ParentPseudoJets was a bit more explicit.

This was tested so far with JetRecAlgTestCfg.py, but we could stand to verify the results vs the older classes.

This MR needs to be handled after !33564 (merged) is merged.