Request: adding `flake8-requirements`

https://github.com/Arkq/flake8-requirements is a plugin for `flake8` that validates the `install_requires` field of a `setup.py`.

It's the last `flake8` plugin I use that's not a part of `ruff`.

It would be great to add this into `ruff`!

Start by reviewing the flake8-requirements project linked in the issue, focusing on how it validates the install_requires field in setup.py. Then inspect Ruff's existing rule implementation and testing patterns to determine where this behavior belongs. Done means Ruff provides equivalent validation for install_requires.

Written by the indexing model from the issue text.