Implement ignorePointerEvents prop for Lua UI widgets

Issue Description

To simplify frustrations with focusGain and focusLoss subscribing to mouse events and pointer hit detection without configuration, needMouseFocus ignorePointerEvents should be implemented as a UI prop.

One issue this would solve is having to manage the focus propagations, or in general the focus resolution, of a button's child widgets which should play no part in something like a hover styling effect.

This prop should be a boolean and default to false

This will configure that particular widget's MyGUI pointer hit detection by calling MyGUI's setNeedMouseFocus() (name has nothing to do with focus)