22.0-FPE_bugfix-PixelDigitization

This addresses ATR-23523, but not yet the related ATLASSIM-5610, by guarding against values to TLorentz::Gamma() which would lead to an FPE, and also the sqrt function in the 'iBetaGamma' calculation directly from the energy loss. I have not investigated why these values can occur, and the class also needs a cleanup which will be the subject of an additional JIRA ticket.