splash effect support

[uwerat]

Material defines 2 different types of visual feedback with the term "ripple". Flutter calls them Highlight and Splash.
Today Splash is implemented for QskPushButton and QskSegmentedBar.

Splash is a temporary effect that is related to the state transition - not to the new state ( Mealy vs. Moore machine ). Maybe it is possible to introduce new types of animation hints to be able to declare this type of transitions in the skin - instead of having extra code in the controls.