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/DataTable/TableRow.svelte

@@ -1,20 +1,15 @@
 <script>
-  let className = undefined;
-  export { className as class };
   export let isSelected = false;
-  export let style = undefined;
-
-  import { cx } from '../../lib';
 
   // TODO: include ariaLabel, onExpand, isExpanded, isSelected
 </script>
 
 <tr
+  class:bx--data-table--selected={isSelected}
+  {...$$restProps}
   on:click
   on:mouseover
   on:mouseenter
-  on:mouseleave
-  class={cx(isSelected && '--data-table--selected', className)}
-  {style}>
+  on:mouseleave>
   <slot />
 </tr>