Rollup merge of #117891 - compiler-errors:recover-for-dyn, r=davidtwco

Recover `dyn` and `impl` after `for<...>`

Recover `dyn` and `impl` after `for<...>` in types. Reuses the logic for parsing bare trait objects, so it doesn't fix cases like `for<'a> dyn Trait + dyn Trait` or anything, but that seems somewhat of a different issue.

Parsing recovery logic is a bit involved, but I couldn't find a way to simplify it.

Fixes #117882

compiler/rustc_parse/src/errors.rs

@@ -2827,3 +2827,23 @@ pub(crate) struct GenericArgsInPatRequireTurbofishSyntax {
     )]
     pub suggest_turbofish: Span,
 }
+
+#[derive(Diagnostic)]
+#[diag(parse_transpose_dyn_or_impl)]
+pub(crate) struct TransposeDynOrImpl<'a> {
+    #[primary_span]
+    pub span: Span,
+    pub kw: &'a str,
+    #[subdiagnostic]
+    pub sugg: TransposeDynOrImplSugg<'a>,
+}
+
+#[derive(Subdiagnostic)]
+#[multipart_suggestion(parse_suggestion, applicability = "machine-applicable")]
+pub(crate) struct TransposeDynOrImplSugg<'a> {
+    #[suggestion_part(code = "")]
+    pub removal_span: Span,
+    #[suggestion_part(code = "{kw} ")]
+    pub insertion_span: Span,
+    pub kw: &'a str,
+}