fANOVA: Implement faster version

[sarah-segel]

As the current implementation of fANOVA is rather inefficient, we could think about how to make it faster.

[eddiebergman]

FYI, I've used this to great effect before: https://github.com/benfred/py-spy

You can generate output for speedscope which you can upload and navigate here: https://www.speedscope.app/

[nabenabe0928]

Talking about the fast version of fANOVA, I implemented fANOVA with another surrogate model (kernel density estimators).

Paper: https://arxiv.org/abs/2304.10255 Implementation: https://github.com/nabenabe0928/local-anova