deprecate a few commands in global namespace #27066
Description
extracted from #25383
- designs_from_XML, designs_from_XML_url
- backtrack_all
- berlekamp_massey
- buzzard_tpslopes
- convergents
Component: refactoring
Author: Frédéric Chapoton
Branch/Commit: b1768f2
Reviewer: Travis Scrimshaw
Issue created by migration from https://trac.sagemath.org/ticket/27066