fix(language-service): Insert parentheses for method completion (#33860)

This commit leverages the `insertText` field in `ts.CompletionEntry` to
return a completion text for class methods that includes parentheses.

PR closes https://github.com/angular/vscode-ng-language-service/issues/15

PR Close #33860

packages/language-service/src/completions.ts

@@ -442,6 +442,7 @@ class ExpressionVisitor extends NullTemplateVisitor {
         name: s.name,
         kind: s.kind as ng.CompletionKind,
         sortText: s.name,
+        insertText: s.callable ? `${s.name}()` : s.name,
       });
     }
   }