Add canonical class diagnostics

[thecrypticace]

This feature is off by default due to performance and memory considerations. It's also possible that this won't even be the final version of this.

We've internally discussed linting per class list instead of per class along with some other stuff but getting this here to test.

Tests won't pass in CI until we have at least an insiders build to test with.

• Needs accompanying code actions to replace the class with the suggested one