basic element and parent for k-regular sequences #21203
Description
Implement minimal element and parent classes for working with k-regular sequences
See also Meta ticket #21202.
Depends on #21164
Depends on #21180
Depends on #21200
Depends on #21295
Component: combinatorics
Author: Daniel Krenn
Branch/Commit: d532b56
Reviewer: Clemens Heuberger
Issue created by migration from https://trac.sagemath.org/ticket/21203