Add option to skip rescaling of original states

[sdahdah]

Scale only lifted states without rescaling original states? Maybe the PolynomialLiftingFn should handle its own scaling.

Either way, it's becoming more clear that normalizing and standardizing should be done outside of the KoopmanPipeline, or within each lifting function as needed. But having a "normalizing" lifting function is a bit awkward since we want to keep the original state inside the lifted state unmodified.

[sdahdah]

I think, for now, normalizing/standardizing data should be done outside of the Koopman pipeline. The second-best option is for PolynomialLiftingFn to rescale its lifted states without rescaling the original state. But this could get confusing and messy. It could also lead to weird weighting issues if the lifted states are way smaller than the original states.