Add the Option to AttributeFilter for a Single Default Output Port

The AttributeFilter has four default output ports: <Empty>, <Missing>, <Null>, and <Unfiltered>. It would be nice to have the option of a single output port instead of these four.

This is because I don’t need to differentiate between <Empty>, <Missing>, <Null>, and <Unfiltered>. They can all go to <Unfiltered> and the transformer would take up less space in my workbench.