New e gamma correction variable master
This MR introduces a new package EGammaVariableCorrection dedicated to the correction of EGamma-related variables (mainly shower shapes) at derivation level. The tools in this package were located in ElectronPhotonShowerShapeFudgeTool in 21.2 and were added in this MR !30290 (merged).
As EGamma might want to go from ElectronPhotonShowerShapeFudgeTool to this new package, the configuration to "fudge" the photons, used in release 21.2, as been ported to this new tool and checks were made on derivation, using master,2020-12-06T2101, that the new tool and the old fudging tool give identical results.
This tool has no client for the time being, but will probably be used in DerivationFrameworkEGamma.