Slider tooltip: New extension to render a tooltip above the slider which moves with the button, displaying the value along the way.

Adapted from https://github.com/web-ui-fw/web-ui-fw/tree/e9ac5c21d2f75b5a68acb2c9d9e7f90494cf0512/src/widgets/slider/
Slider tooltip: Move to demos
Demos: Adding slider tooltip demo