TableEditor 'menu_name' not implemented for Qt

As far as I can tell this only implemented for Wx, but no indication of this is given in the trait description. I think this functionality can be added by inserting something like:
```python
if menu_manager is None:
menu_manager = getattr(editor.object, editor.factory.menu_name, None)
```
around these parts:
https://github.com/enthought/traitsui/blob/5d233f577b2834b83ae7336897a230b6b5ef4dfd/traitsui/qt4/table_editor.py#L1011-L1014