Learned Interior Input Keypoints For Numerical Calibrators

[willbakst]

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About:

Sometimes learned input keypoints can enable learning a better function because the calibrator is more flexible. This is especially true for output calibrators where you can't initialize based on quantiles (and learning input keypoints during training could be valuable compared to e.g. uniformly initialized keypoints).

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Is your feature request related to a problem? Please describe.
Not a problem, just an enhancement.

Describe the solution you'd like
Enable learned interior keypoints for numerical calibrators through a constructor argument for input keypoint type.

Describe alternatives you've considered
None, this is the known implementation.

Additional context
N/A