Ability to pass in event handlers to Slider component

**Is your feature request related to a problem? Please describe.**
The slider component doesn't seem to provide a way to respond to it's movements.

**Describe the solution you'd like**
It would be great to be able to pass in a callback function as a prop to the slider that accepts as a parameter the percentage that the slider has moved fro left to right. This callback would be executed every time the slider moved.

**Describe alternatives you've considered**
This could be done perhaps using refs and DOM event handlers, but it would be a hack.

**Additional context**
https://rimble.consensys.design/components/rimble-ui/Slider