[3.9] bpo-32631: IDLE: Enable zzdummy example extension module (GH-14… by terryjreedy · Pull Request #24114 · python/cpython

…nGH-14491)

Make menu items work with formatter, add docstrings, add 100% tests.

Co-authored-by: Terry Jan Reedy <tjreedy@udel.edu>
(cherry picked from commit e40e2a2)

Co-authored-by: Cheryl Sabella <cheryl.sabella@gmail.com>