refactor: use $$restProps API

- add ref prop for applicable components (#196)
- add slot to Content Switcher `Switch` component (#183)
- remove fillArray, css utilities

src/components/Icon/Icon.Skeleton.svelte

@@ -1,16 +1,12 @@
 <script>
-  let className = undefined;
-  export { className as class };
   export let size = 16;
-  export let style = undefined;
-
-  import { cx, css } from '../../lib';
 </script>
 
 <div
+  class:bx--icon--skeleton={true}
+  {...$$restProps}
+  style="{$$restProps.style}; width: {size}px; height: {size}px"
   on:click
   on:mouseover
   on:mouseenter
-  on:mouseleave
-  class={cx('--icon--skeleton', className)}
-  style={css([style, ['width', `${size}px`], ['height', `${size}px`]])} />
+  on:mouseleave />