Auto merge of #74210 - estebank:type-ascriptomatic, r=petrochenkov

Deduplicate `::` -> `:` typo errors

Deduplicate errors caused by the same type ascription typo, including
ones suggested during parsing that would get reported again during
resolve. Fix #70382.

src/librustc_parse/parser/diagnostics.rs

@@ -333,6 +333,7 @@ impl<'a> Parser<'a> {
                         Applicability::MachineApplicable
                     },
                 );
+                self.sess.type_ascription_path_suggestions.borrow_mut().insert(sp);
             } else if op_pos.line != next_pos.line && maybe_expected_semicolon {
                 err.span_suggestion(
                     sp,