overlap filter for PFCands at HLT

Adds a filter that runs on a collection of PF Cands and removes those that overlap with another collection.
The use case is for L3 muons in HLT paths with PF iso, which are seen to occasionally overlap with PF Hadrons.  Hopefully going to be a temporary fix until the PF behavior there is fully understood.

No existing modules are touched.  Ideally would go into 70X, if possible..