gh-133653: Fix argparse.ArgumentParser with the formatter_class argument (GH-133813)

* Fix TypeError when formatter_class is a custom subclass of
  HelpFormatter.
* Fix TypeError when formatter_class is not a subclass of
  HelpFormatter and non-standard prefix_char is used.
* Fix support of colorizing when formatter_class is not a subclass of
  HelpFormatter.
* Remove the prefix_chars parameter of HelpFormatter.