We add spkg-configure for the optional package cbc.

Because OptionalExtension does not know about packages found by spkg-configure (see #25828), this is only useful on top of #28175.

Depends on #28175
Depends on #27870

CC: @dimpase

Component: packages: optional

Author: Matthias Koeppe

Branch/Commit: 2b07cf5

Reviewer: Dima Pasechnik

Issue created by migration from https://trac.sagemath.org/ticket/28908