sage.rings.all has a mixture of generic classes and implementation classes. Some of the generic and/or basic ones will probably have to be included in sage-objects (#29865). We prepare this by getting rid of imports from sage.rings.all throughout sage.categories.
CC: @tscrim
Component: refactoring
Author: Matthias Koeppe
Branch/Commit: 82676e6
Reviewer: Travis Scrimshaw, Frédéric Chapoton
Issue created by migration from https://trac.sagemath.org/ticket/29881