GH-83162: Rename re.error for better clarity. (#101677)

Renamed re.error for clarity, and kept re.error for backward compatibility.
Updated idlelib files at TJR's request.
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Co-authored-by: Matthias Bussonnier <mbussonnier@ucmerced.edu>
Co-authored-by: Hugo van Kemenade <hugovk@users.noreply.github.com>
Co-authored-by: Terry Jan Reedy <tjreedy@udel.edu>