MAINT, DOC: make np._from_dlpack public

[tirthasheshpatel]

fixes gh-20743

This PR:

• Makes np._from_dlpack public.
• Adds docs for the DLPack protocol in the user guide section "Interpolability with NumPy"

cc @seberg @mattip @leofang

@melissawm this might interest you :)

[charris]

Won't this break backwards compatibility? Perhaps we should keep both names for a bit while deprecating the underscored version.

[tirthasheshpatel]

Won't this break backwards compatibility?

I didn't expect backward compatibility would be a concern for private methods (_from_dlpack wasn't even documented before). The reason we kept _from_dlpack private was that the protocol wasn't formally documented anywhere and there were a few bugs. Do you think it's OK not to worry about backward compatibility given the above reasons? If not, I can keep both the versions :)

[mattip]

Could you add a note in doc/release/upcoming_changes? There is a README there which should explain how to add a new_feature.rst

[tirthasheshpatel]

Added the function to upcoming changes @mattip!

[mattip]

LGTM. Let's wait a day or so to see if the mailing list discussion leads to changes.

The rendered documentation can be seen here

[tirthasheshpatel]

The one failure seems unrelated.

[mattip]

Thanks @tirthasheshpatel

[tirthasheshpatel]

Thanks @mattip @charris @leofang for the reviews!