deprecate import of all_max_clique, max_clique and clique_number in global namespace #26200
Description
As part of #25383, deprecate import of all_max_clique, max_clique and clique_number into global namespace. These methods are already methods of Graph.
Component: graph theory
Author: David Coudert
Branch/Commit: ab7d219
Reviewer: Frédéric Chapoton
Issue created by migration from https://trac.sagemath.org/ticket/26200