Remove use of com.sun.javafx.scene.control.behavior.* classes

[abhinayagarwal]

With #1395, we removed the use of Behavior classes from RangeSlider and SnapshotView, there is just one control which has a dependency on the com.sun.javafx.scene.control.behavior.* class i.e. GridViewBehavior.

It is complex to fix GridViewBehavior as it extends TableViewBehavior instead of BehaviorBase.

@Maxoudela can you have a quick look to see if we can do something about this class?

[Maxoudela]

Well.. There is quite a lot of code inside TableViewBehavior and TableViewBehaviorBase.
If we want to get rid of the dependencies, it means I have to get rid of the GridViewBehavior.
This also means I have to extends from TableViewSkin instead of TableViewSkinBase in the GridViewSkin (in order to have a TableViewBehavior constructed).

I can have access to some methods in the TableViewSkin, but some are missing. For example discontinuousSelectNextColumn() that is in the Behavior and that I need to override if I want the selection to work properly with the span.

If you have some ideas, let me know