bpo-45296: Fix exit/quit message on Windows (GH-28577) (GH-28600)

IDLE recognizes Ctrl-D, as on other systems, instead of Ctrl-Z.
(cherry picked from commit e649e0658ff2af87b07d994c05ae048e16e31aae)

Co-authored-by: Terry Jan Reedy <tjreedy@udel.edu>