bpo-33906: Rename idlelib.windows as window (GH-7833)


Match Window on the main menu and remove last plural module name.
Change imports, test, and attribute references to match new name.
(cherry picked from commit a361e89d5ae3daefe9e8b8a7e889cd2ad8c45b77)

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