[Extensions.ML] AddPredictionEnginePool should support models as embedded resources

Today AddPredictionEnginePool supports `FromFile` and `FromUri`. Another scenario is to add the ML model as an embedded resource in a project, so you don't have to worry about copying and finding a file - it will always be in the code assembly. Or potentially you may have different models for different languages, and you can replace the resource depending on the current culture.

We should add suport for embedded resource files to Extensions.ML.