[ENH] A modular approach to constructing forests that have permuted covariates

[adam2392]

This may eventually replace FeatureImportance* if we need it to.

Changes proposed in this pull request:

• We separate the training of a permuted forest and the final computation of a pvalue
• I will also enable the permutation of covariates within Cython if the power computation experiment determines bootstrapping is better.
• Adds oob_samples_ to any forest that is fit with bootstrap on

The forests should be classes without too much logic addition and the pvalue computation logic can be wrapped into a function.

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[codecov]

Codecov Report

Attention: 16 lines in your changes are missing coverage. Please review.

Comparison is base (aa655d6) 88.29% compared to head (39f3db7) 88.45%.

❗ Current head 39f3db7 differs from pull request most recent head a9192f9. Consider uploading reports for the commit a9192f9 to get more accurate results

Files	Patch %	Lines
sktree/stats/forestht.py	26.31%	14 Missing ⚠️
sktree/ensemble/_extensions.py	96.66%	2 Missing ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##             main     #211      +/-   ##
==========================================
+ Coverage   88.29%   88.45%   +0.16%     
==========================================
  Files          50       54       +4     
  Lines        4646     4825     +179     
==========================================
+ Hits         4102     4268     +166     
- Misses        544      557      +13     

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[PSSF23]

LGTM if checks all pass.