make require_one_based_indexing part of the API

[tpapp]

#30630 introduced the convenience function Base.require_one_based_indexing, which is very useful for conveying intent in assertions.

I propose that this is made part of the official API for, ideally, the 1.2 release. Not necessarily exported (to keep the namespace clean), just documented.

[tpapp]

@KristofferC, can you explain why you don't think it is a good idea?

[KristofferC]

has_offset_axes is already documented and anyone who needs this can just write their own function on top of that. The function has an ugly name, it will likely rarely be used and it doesn't seem worth exposing.

[mkitti]

This suggests that we should remove mention of Base.require_one_based_indexing from the documentation and prefer has_offset_axes.

[johnnychen94]

#43263 already documented it during the discussion on Yuri's blog so I figure this should be closed.