Improve pip's CLI help using rich colors

[hamdanal]

What's the problem this feature will solve?

Reading the help of a large CLI like pip can sometimes be difficult because of the amount of information displayed on the screen. pip already improve on the default optparse help formatters by using a custom PrettyHelpFormatte. I think the help text can be made even more easier to read by using different colors for the section titles and for the command line arguments.

Describe the solution you'd like

With rich already vendored by pip, it is a fairly straight forward to improve the situation. I'd like to propose a PR adding this if there is no objection from the maintainers. I expect the change to be minimal since pip already does of the customization work already and the heavy lifting is done by rich.

Alternative Solutions

Do nothing, the current situation is good enough.

Additional context

I have a working optparse formatter with colors here https://github.com/hamdanal/rich-argparse/blob/main/rich_argparse/optparse.py. The change will be based on this formatter but modified per pip's custom requirements.

Code of Conduct

• I agree to follow the PSF Code of Conduct.