Use case

The slider_theme.dart is file is pretty bloated already and I'm going to update RangeSlider to new M3 redesign which means adding even more components to this file.

https://github.com/flutter/flutter/blob/master/packages/flutter/lib/src/material/slider_theme.dart

It has been suggested that we could move Slider and RangeSlider components into a separate file. Maybe it could be called sliders_components.dart?

Proposal

Move Slider and RangeSlider components from slider_theme.dart into a separate file.