CppEditor: Add quickfix for converting comments from C++ to C style

... and vice versa.

Fixes: QTCREATORBUG-27501
Change-Id: I8584cc1e86718b3fe0f0ead2a3436495303ca3c8
Reviewed-by: <github-actions-qt-creator@cristianadam.eu>
Reviewed-by: David Schulz <david.schulz@qt.io>

src/plugins/cppeditor/cppquickfix_test.h

@@ -219,6 +219,9 @@ private slots:
 
     void testGenerateConstructor_data();
     void testGenerateConstructor();
+
+    void testChangeCommentType_data();
+    void testChangeCommentType();
 };
 
 } // namespace Tests