Making TFCSParametrizationBase::simulate method const

This merge request makes the TFCSParametrizationBase::simulate method const. It also makes a few local variables const in ISF_FastCaloSimEvent classes to allow the compiler to optimize the code more easily.

This also allows IFastCaloSimParamSvc::simulate to be made const.

Depends on !28517 (merged). The same changes will be merged into master in !28525 (merged)