gh-95471: IDLE - Tweak Edit menu (GH-95481)

Move `Select All` above  `Cut` as it is used with `Cut` and `Copy` but not `Paste`.  Add a separator between `Replace` and `Go to Line` to separate items that belong to the 'Edit-find' (above) and 'Edit-show' (below) IDLE github project topics.
(cherry picked from commit 53357b3e)

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