[3.14] gh-133653: Fix argparse.ArgumentParser with the formatter_class argument ...

[3.14] gh-133653: Fix argparse.ArgumentParser with the formatter_class argument (GH-133813) (GH-133941)

* 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.
(cherry picked from commit 734e15b70dc044f57df4049a22dd769dffdb7d18)

Co-authored-by: Serhiy Storchaka <storchaka@gmail.com>