full `# noqa` support

[jakkdl]

Making a separate issue from #181 to track all current issues/TOODs with # noqa

• 0 Respect noqa-trio as a way to have full flake8-noqa support
• [ ] 1 Don't autofix noqa'd errors
  • This might not be a huge issue atm, but is a must going forward as more visitors get autofix support.
• [ ] 2 Raise error if invalid (or not enabled) TRIO error code is noqa'd.
  • Not a must, and sort of covered by flake8-noqa. But if it's a simple logic addition there's not much reason not to.
• [x] 3 raise noqad errors when running as a plugin #188
  • otherwise we're fully incompatible with flake8-noqa
• [ ] 4 support --disable-noqa
• [ ] 5 document current level of [in]compatibility with flake8-noqa
• [x] 6 respect # noqa in ast visitors. #188
• [ ] 7 check that # noqa comments are resilient to line numbers changing due to autofix.