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/cppquickfixes.h

@@ -585,5 +585,13 @@ private:
     bool m_test = false;
 };
 
+//! Converts C-style to C++-style comments and vice versa
+class ConvertCommentStyle : public CppQuickFixFactory
+{
+private:
+    void match(const CppQuickFixInterface &interface,
+               TextEditor::QuickFixOperations &result) override;
+};
+
 } // namespace Internal
 } // namespace CppEditor