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>
diff --git a/Lib/idlelib/browser.py b/Lib/idlelib/browser.py
index 447dafc..234883f 100644
--- a/Lib/idlelib/browser.py
+++ b/Lib/idlelib/browser.py
@@ -16,7 +16,7 @@
 from idlelib.config import idleConf
 from idlelib import pyshell
 from idlelib.tree import TreeNode, TreeItem, ScrolledCanvas
-from idlelib.windows import ListedToplevel
+from idlelib.window import ListedToplevel
 
 
 file_open = None  # Method...Item and Class...Item use this.