ENH: add support for `nanmin`, `nanmax`, `nanmean` and `nansum`

[OmarManzoor]

Would it make sense to include these

• nanmin
• nanmax
• nanmean
• nansum

There is a corresponding issue opened in data-apis/array-api#621 but I don't think that has been planned yet.

scikit-learn reference: array api nan reduction utils

What do you think @lucascolley

[lucascolley]

feel free to add to the agenda at https://hackmd.io/zn5bvdZTQIeJmb3RW1B-8g (even if you can't make it to the meeting it could still be discussed)

[OmarManzoor]

@lucascolley Would it be okay if you could add it please? Because otherwise editing the agenda that you shared requires signing up and I don't really use this platform.