ENH: Added sanity check to printoptions

[Mitchell-Faas]

See issue #18254

[rgommers]

Restarting CI, something weird happened.

[eric-wieser]

Perhaps better as precision = operator.index(precision), else this blows up if users pass an np.int32 or something else that's harmless

[eric-wieser]

I think we normally don't do from operator import *, as those names are very likely to overlap with other names. If nothing else, it makes operator.index something which can be searched for.

[BvB93]

Can you update the annotations in arrayprint.pyi as well?

In total two changes will be necessary:

1. Import the SupportsIndex protocol right here:

if sys.version_info > (3, 8):
    from typing import SupportsIndex
else:
    from typing_extensions import SupportsIndex

2. Replace int with SupportsIndex (for the precision parameter) in the following functions:

• set_printoptions
• array2string
• array_repr
• array_str
• printoptions

[BvB93]

The annotation update is looking good as well.

[charris]

Thanks @Mitchell-Faas .