[ALOY-1701] XML: Unable to use platform namespace restriction on event handlers

Description

ALOY-1646 introduced support for namespacing an xml attribute to restrict a property to a single platform, this does not work for event handlers as they are handled separately to where this is done.

<Alloy>
	<Window android:onClick="doClick">
	</Window>
</Alloy>

function doClick(e) {
	console.log('clicky click')
};

$.index.open();

Steps to reproduce

1. Add the above to your index.xml/index.js files 2. Build to Android

Actual

No event listener is attached

Expected

Event listener should be attached