Remove duplicate headers
As discussed in !30787 (merged) (this thread) with @christos, there are two (nearly) duplicate headers in ElectronPhotonShowerShapeFudgeTool and in ElectronPhotonSelectorTools.
I moved and merged these two (nearly) duplicate private headers to ElectronPhotonID/EgammaAnalysisHelpers, so that now there is one shared public header.
Edited by Nils Gillwald