Readds `@next/next/no-assign-module-variable` ESLint rule that was inadvertently removed in #34335 during the resolution of many merge conflicts.
This PR will get us back to a good / working state. I'll see if I can add a test to ensure all rule are accounted for in a separate PR.
Fixes#34335.
## Bug
- [x] Related issues linked using `fixes #number`
- [x] Integration tests added
- [x] Errors have helpful link attached, see `contributing.md`
## Documentation / Examples
- [x] Make sure the linting passes by running `pnpm lint`
- [x] The examples guidelines are followed from [our contributing doc](https://github.com/vercel/next.js/blob/canary/contributing.md#adding-examples)
