ISF_FastCaloSimParametrization: cmake cleanup, enable flake8

...FastCaloSim/ISF_FastCaloSimParametrization/CMakeLists.txt

...etrization/python/ISF_FastCaloSimParametrizationConfig.py

...rization/python/ISF_FastCaloSimParametrizationConfigDb.py

...metrization/python/ISF_NativeFastCaloSimServicesConfig.py

...astCaloSimParametrization/python/ShowerShapeRegression.py

...loSim/ISF_FastCaloSimParametrization/python/fcsTrfArgs.py