CaloExtensionTool . Use same as Rel 21 when we want the electron extrapolation strategy.
requested to merge ATLAS-EGamma/athena:caloExtension_for_electron_extrapolation_use_the_last_measurement_from_TrackParticle_when_available_AOD into master
CaloExtensionTool . Use same as Rel 21 when we want the extrapolation strategy for electrons. Also add comments to explain a bit the 'strategies' we have