Implement basic input validation for built-in attributes Correct top-level shape (`#[attr]` vs `#[attr(...)]` vs `#[attr = ...]`) is enforced for built-in attributes, built-in attributes must also fit into the "meta-item" syntax (aka the "classic attribute syntax"). For some subset of attributes (found by crater run), errors are lowered to deprecation warnings. NOTE: This PR previously included https://github.com/rust-lang/rust/pull/57367 as well.