Make PhysicsLists runtime configurable

The ActsFatras::PhysicsLists always runs all compile-time configured processes. However, sometimes you want to enable/disable some of the processes at runtime as well. The current workaround adds boolean flags explicitely to all processes. Instead, processes should be configurable at the physics lists level. The interface could look something like this:

PhysicsList<Scattering, EnergyLoss> pl;
pl.disableAll();
pl.enableAll();
pl.disable<Scattering>();
pl.enable<EnergyLoss>();