gh-91832: Add 'required' attr to argparse.Action repr (GH-91841)

GH- Adding 'required' to names in Lib.argparse.Action

gh-91832:
Added 'required' to the list `names` in `Lib.argparse.Action`.
Changed constant strings that test the Action object.

Automerge-Triggered-By: GH:merwok
(cherry picked from commit 4ed39000)

Co-authored-by: Abhigyan Bose <abhigyandeepbose@gmail.com>