bpo-44026: Idle - display interpreter's 'did you mean' hints (GH-25912)

A C function accessible by the default exception handler, but not by python code,
finds the existing name closest to the name causing a name or attribute error.  For
such errors, call the default handler after capturing stderr and retrieve its message line.

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