Add JetGhostLabel to StandardSmallRJets truthmods

I'm adding flavor labeling based on ghost association to all the small-R jet collections that get truthmods. They already get our delta-R based labeling info, which is presumably only needed for flavor tagging, but flavor tagging plans to move to ghost association so we should add the ghost labels for consistency.

That's only part of the reason for this MR though, which was initiated by a discussion with @sschramm about how to get flavor labels on pileup jets.

The flavor labeling for reconstructed jets happens when we build the jet collection, and uses the hard-scatter truth record. This means we have no labeling for pileup jets (the truth record for those isn't saved). The workaround is to use the flavor labeling we store in InTime truth jets. These jets (like most other jet collections) currently only store the delta-R labels.

Modifying the InTime truth jets means going pretty far up the reconstruction (simulation?) chain, unfortunately, so I'm making this MR to 24.0 just in case we ever do a reprocessing with this release.

As ready since the JetMet conveners seem cool with it. Also tagging @robouque, @ligang (FTAG software) and @stapiaar, @bhodkins (jet software).