Rollup merge of #89090 - cjgillot:bare-dyn, r=jackh726

Lint bare traits in AstConv.

Removing the lint from lowering allows to:
- make lowering querification easier;
- have the lint implementation in only one place.

r? `@estebank`

compiler/rustc_lint_defs/src/lib.rs

@@ -285,7 +285,6 @@ pub enum ExternDepSpec {
 #[derive(PartialEq, Debug)]
 pub enum BuiltinLintDiagnostics {
     Normal,
-    BareTraitObject(Span, /* is_global */ bool),
     AbsPathWithModule(Span),
     ProcMacroDeriveResolutionFallback(Span),
     MacroExpandedMacroExportsAccessedByAbsolutePaths(Span),