89baf0f162
rustc_lint: Some early linting refactorings The first one removes and renames some fields and methods from `EarlyContext`. The second one uses the set of registered tools (for tool attributes and tool lints) in a more centralized way. The third one removes creation of a fake `ast::Crate` from `fn pre_expansion_lint`. Pre-expansion linting is done with per-module granularity on freshly loaded modules, and it previously synthesized an `ast::Crate` to visit non-root modules, now they are visited as modules. The node ID used for pre-expansion linting is also made more precise (the loaded module ID is used).
For more information about how rustc works, see the rustc dev guide.