Support namespaced dictionary packages

[Stealthii]

In an attempt to clean up common acronym and product name misspellings across various projects, it would be nice to provide auto-discovery of namespaced packages that contain dictionary definitions of various spellings.

As an example for the FooBar company, if I wanted to include a pre-commit dependency foobar-codespell, that provided the following dictionaries under a namespace:

src/codespell/contrib/foobar/__init__.py  # potential required export definitions
src/codespell/contrib/foobar/data/dictionary.txt
src/codespell/contrib/foobar/data/dictionary_product.txt

References to these as an aside to builtin via a new option contrib, such as the following:

builtin = "clear,usage,en-GB_to_en-US"
contrib = "foobar,foobar.product"

[Stealthii]

This is a feature request, not a bug. The implementation specifics do not need to match my example, but I'm interested in discussion on how this could work, if the project was to consider such a feature.