add visibilty properties to extended state explictily

Because of the nasty side effects described here

https://bugreports.qt.io/browse/QTBUG-31914

https://bugreports.qt.io/browse/QTBUG-40333

It is possible for a stack view or layout to set the sub components of an exported design to visible false, and because it is not set explicitly true it will never go to visible.

Attached Screenshot, video and code example of this effect in action.

As it seems clear that Qt Declarative will not fix this because they do not consider this a bug but rather an "undesirable behavior" - or rather, imo, bad design.

Either way it falls on us to implement a workaround for qt bridge that involves explicitly creating the default visibility properties, both true and false, in the state from which we extend.