[New feature] Inherit attached properties

[mangoyoga80]

When implementing a lot of drag and drop within an application, there are some repetition when it comes to some of the properties that are assigned, such as UseDefaultDragAdorner, DragAdornerTemplate, ShowAlwaysDropTargetAdorner, etc, I'm wondering if perhaps these could be set as inherited, so that they can be set at the top level window rather than on each individual droptarget/DropSource. While this change may introduce some unexpected behaviors where the current defaults are relied upon, it could be introduced by new properties UseDefaultDragAdornerInherited, and modify the TryGet methods to use the inherited default if set. perhaps these properties have to be nullable so that fewer unintended consequences are introduced?