Add entrypoint for PFI (dotnet#4232)

* Add entrypoint for PFI

* Regenerate EP catalog

* Add tests

* Adding Standard Error of Mean to PFI Metrics in EntryPoint

* PR Feedback

* Remove MLContext from EntryPoint

* Use last predictor in the model if model.LastTransformer is not a predictor

* nit

* Model file path conflicts in tests

* nit

* PR Feedback

* Pass in model as PredictorModel

* Remove label column and group ID column from entrypoint input arguments

* nit

* Simplify data prep