Egamma add flags on topo related thresholds. Allow to easily override things e.g for UPC

Egamma add flags on topo related thresholds. Allow to easily override things e.g for UPC

Let me ping @igrabows and @yvolkotr

1. ) I added the thresholds one might want to modify for UPC as flags. The ones here should be the current p-p defaults

2. ) @tbold @tadej might know more on how is best to set it up for a custom reco . Depends on how is planned but in principle in UPC reco you prb want to run egamma per se with these set in some other/lower values.

3. ) As an aside the egamma CI tests are here https://gitlab.cern.ch/atlas/athena/-/blob/master/AtlasTest/CITest/Athena.cmake#L149 new and old style.

4. ) There is a catch if you run old style, in that although egamma is fully new style , inner detector is not. But did not want to invent an new old style flag for this [https://acode-browser1.usatlas.bnl.gov/lxr/source/athena/InnerDetector/InDetExample/InDetRecExample/share/InDetRecCaloSeededROISelection.py#0019]. So you will need prb something manual in old style still .... In new style InDet would pick up the flag as it calls the same egamma ... Cfg

Now I assume I did the defaults correctly. But the CI will tell us ...