make divmod() work for more rings

[yyyyx4]

Python's divmod() is only supported for EuclideanDomainElements in Sage, whereas .quo_rem() is more universal.

It is worth noting that

• some rings implement .quo_rem(), //, % despite not being Euclidean domains (example: ZZ['x']); and
• not even all elements of Euclidean domains are instances of EuclideanDomainElement (example: QQ['x']).
  Therefore, divmod() will often not work when it should.

This patch moves .__divmod__() up from EuclideanDomainElement to RingElement, which makes divmod() work for more rings. Of course, not all rings have division with remainder implemented, but we can simply let that fail in the callee.

Short mailing list discussion: https://groups.google.com/g/sage-devel/c/GlTlFkQCQ0M

CC: @roed314 @kcrisman

Component: algebra

Author: Lorenz Panny

Branch/Commit: 778bef3

Reviewer: Travis Scrimshaw

Issue created by migration from https://trac.sagemath.org/ticket/33704

[yyyyx4]

Branch: public/move_divmod_up_to_RingElement

[yyyyx4]

Commit: 778bef3

[yyyyx4]

New commits:

778bef3

move .__divmod__() up to RingElement

[tscrim]

Reviewer: Travis Scrimshaw

[tscrim]

comment:3

Author name. ;) Once that is done, the patchbot will run. If that comes back green, then you can set a positive review.

[yyyyx4]

comment:4

Oops! :)

[yyyyx4]

Author: Lorenz Panny

[yyyyx4]

comment:5

Bot seems green enough. Thanks!

[vbraun]

Changed branch from public/move_divmod_up_to_RingElement to 778bef3