Add WrappedColorFormatter to contrib.

[jlevy]

Thanks for the great lib. A peeve of mine is that it can be hard to read argparse help on wide terminals. This is my preferred formatter now for my projects so thought I'd add it to contrib!

[RomainBrault]

Currently you can also get the same result with functools.partial.

[hamdanal]

Thanks for your contribution.
Text width is a property that affects all formatters, it should not have its own formatter. There are many solutions that work now:

1. You can use a lambda, functools.partial or a subclass of your favorite formatter to set the width as suggested by the comment above
2. The better option is to set the COLUMNS variable in your shell's dotfiles and have all your terminal output wrapped to your favorite terminal width. This is the best option as this way you don't impose your choice of narrow screen on users of your tools (plus this will work for tools that don't use rich-argparse).

I don't think this should be in rich-argparse. If you disagree we can look into ways to make it usable with all formatters, no new formatter needs to be defined. Before we do though, we should look to see if there is an existing standard or convention similar to the $COLUMNS var that sets the maximum width.