Otsu thresholding admits hist as input parameter on v0.19.0 while multi-Otsu does not

[andres-fr]

Description

As it can be seen in the API docs for version 0.19.0.dev0, multi-Otsu still has the older signature, while 2-class Otsu has the newer one:

https://scikit-image.org/docs/dev/api/skimage.filters.html#skimage.filters.threshold_otsu
https://scikit-image.org/docs/dev/api/skimage.filters.html#skimage.filters.threshold_multiotsu

Feeding the histogram directly has many advantageous use cases, one of them is extracting thresholds for multiple images at the same time (e.g. for video sequences). The feature requested here is to update the signature for multi-Otsu to accept histograms as well.

Currently there is another PR open on multi-Otsu, awaiting integration: #5198

I've proposed a workaround there and the author proposed to submit a new, separate PR.
I've opened this issue to introduce and sustain the new PR that I hope to submit in the following days.

Way to reproduce

This issue is about interfaces and doesn't involve any particular implementation.

Version information

As mentioned above, the signature inconsistency happens at least in skimage version 0.19.0.dev0.