Fast TRT digitization new tunings
Updated tuning of the efficiency and resolution parameters. This should improve the discrepancies seen in the last Physics Validation round (https://indico.cern.ch/event/781298/). Also, the numerical parameters scatted in the source code have been moved to a dedicated method.
The code compiles and runs with the last 21.3 nightly (2019-04-07T2151).