[WIP] Adding initial model based feature importance

[ctr26]

modified from EmbeddedArtistry

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• Enhancement (adds functionality).
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Hi all,

I've unintentionally been working on my own similiar code base for years. If it's ok with you I'm going to upstream some of the code and modules that I think you're currently missing that would be helpful, particularly around extracting feature importances and model fitting. Hoping this is ok.

[gwaybio]

Thanks @ctr26 , we certainly welcome your contributions and we'd be delighted to include them!

We'll be happy to review this PR when it's ready, and we highly recommend adding functionality bit by bit. This will make review much more streamlined and effective.

I'll also provide two additional notes:

• please review our Contributing guide when you get a chance (if you haven't already of course!)
• we strive for high test coverage, so we are likely to be sticklers about testing

Cheers!