Use span_lint_hir() for more intuitive #[allow(...)] locations

[BD103]

span_lint_hir() can be used to emit a diagnostic for a different HirId, meaning a different location that can be silenced.

This is useful when we check one location for a lint, but emit the diagnostic in a separate location. The user may try #[allow(...)]-ing the lint at that separate location, but nothing will happen. Using span_lint_hir() can avoid this scenario.