feat(slider): add fullWidth prop (#1354)

The `bx--slider` class in the `Slider` component has max-width of `40rem`. Because `$$restProps` is spread to the top-level `div` element in `Slider`, the only way to override the style is to do so globally:

```css
:global(.bx--slider-container) {
  width: 100%;
}

:global(.bx--slider) {
  max-width: none;
}
```

This adds a `fullWidth` prop that sets a full width style using inline style attributes.

docs/src/pages/components/Slider.svx

@@ -11,6 +11,12 @@ components: ["Slider", "SliderSkeleton"]
 
 <Slider />
 
+### Full width
+
+Set `fullWidth` to `true` for the slider to span the full width of its containing element.
+
+<Slider fullWidth />
+
 ### Hidden text input
 
 <Slider hideTextInput />