Move the definition of FastCaloSimIsGenSimulStable in truthutils

Andrii Verbytskyirequested to merge
averbyts/athena:move_to_truthutils into 23.0

Move the definition of FastCaloSimIsGenSimulStable in TruthUtils. Part of an effort to consolidate all the codes that are used for classification of particles.

Edited by Andrii Verbytskyi

Merge request reports