Add keyboard focus visual indicator for slider v2

[c3n9]

Technical Changes

• Added focus state handling in some templates
• Extended ripple effect system to support focus state
• Disabled default focus adorner in favor of Material Design visuals
• Added smooth transitions for focus state changes

But it work only for MaterialSliderV2.

[c3n9]

before (3 focusable elements, lol)

after (1 focusable element)

[SKProCH]

Thanks!