add typo suggestion to unknown attribute error
Provides a suggestion using Levenshtein distance to suggest built-in attributes and attribute macros.
Fixes#49270.
This commit extends existing suggestions to prefix unused variable
bindings in match arms with an underscore so that it applies to all
patterns in a match arm.
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.
Resolve `$crate`s for pretty-printing at more appropriate time
Doing it in `BuildReducedGraphVisitor` wasn't a good idea, identifiers wasn't actually visited half of the time.
As a result some `$crate`s weren't resolved and were therefore pretty-printed as `$crate` literally, which turns into two tokens during re-parsing of the pretty-printed text.
Now we are visiting and resolving `$crate` identifiers in an item right before sending that item to a proc macro attribute or derive.
Fixes https://github.com/rust-lang/rust/issues/57089
