Provide automatic PaletteValue selection

[Zsombor Egri]

The current way to select a color for a component is pretty error-prone. Developers need to select the proper palette value set for each component depending on the component status (enabled, disabled, selected, focused, highlighted). UITK should provide an easy way to do this on styled components level, preferably through a state-agnostic property or style callback. In this way we could immediately spot palette errors on component level, and we wouldn't need to change all components every time we introduce a new value set.