Update TrigEgamma configuration so we can unifye/gamma chains setup functions
This is a MR following tasks discussed in ATR-24210 and ATR-24211.
Here I updated the TrigEgammaKeys definition into not a static class as before but as a base class with default values to configure Electron and Photon chains, and added other classes that will be used to configure _GSF and _LRT variant electron chains.
That class was moved to a diferent file "TrigEgammaKeys" which is new
Also The file "EgammaDefs" was renamed into "TrigEgammaDefs"
In a future MR all files called *_LRT and *_GSF or *_FWD will be removed and its content will removed once their functionalities are implemented in the main files (called the same without the suffix).