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/Tabs/TabsSkeleton.svelte

@@ -1,28 +1,21 @@
-<script>
-  let className = undefined;
-  export { className as class };
-  export let style = undefined;
-
-  import { cx } from '../../lib';
-</script>
-
 <div
+  class:bx--tabs={true}
+  class:bx--skeleton={true}
+  {...$$restProps}
   on:click
   on:mouseover
   on:mouseenter
-  on:mouseleave
-  class={cx('--tabs', '--skeleton', className)}
-  {style}>
-  <div class={cx('--tabs-trigger')}>
-    <div class={cx('--tabs-trigger-text')}>&nbsp;</div>
+  on:mouseleave>
+  <div class:bx--tabs-trigger={true}>
+    <div class:bx--tabs-trigger-text={true}>&nbsp;</div>
     <svg width="10" height="5" viewBox="0 0 10 5" fill-rule="evenodd">
       <path d="M10 0L5 5 0 0z" />
     </svg>
   </div>
-  <ul class={cx('--tabs__nav', '--tabs__nav--hidden')}>
+  <ul class:bx--tabs__nav={true} class:bx--tabs__nav--hidden={true}>
     {#each [0, 1, 2, 3] as item, i (item)}
-      <li class={cx('--tabs__nav-item')}>
-        <div class={cx('--tabs__nav-link')}>&nbsp;</div>
+      <li class:bx--tabs__nav-item={true}>
+        <div class:bx--tabs__nav-link={true}>&nbsp;</div>
       </li>
     {/each}
   </ul>