Rule for cohesion (LCOM4 or similar)

### Summary

Hi! 👋

I was looking at rules that measure cohesion in ruff, and I did not find much.

There is this library https://github.com/mschwager/cohesion, which can work as a flake8 plugin, with a rule (`H601 class has low cohesion`).

Any plans to implement something similar? Or maybe something like this already exists in ruff and I missed it?

Thanks!

Start by reviewing Ruff's existing rule set and the linked cohesion library, especially its H601 flake8 rule. Determine whether a cohesion rule belongs in Ruff and define the intended LCOM4 or similar metric, supported Python constructs, diagnostics, and tests before implementation.

Written by the indexing model from the issue text.