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/Copy/Copy.svelte

@@ -1,38 +1,51 @@
 <script>
-  let className = undefined;
-  export { className as class };
-  export let feedback = 'Copied!';
+  export let feedback = "Copied!";
   export let feedbackTimeout = 2000;
-  export let style = undefined;
+  export let ref = null;
 
-  import { onDestroy } from 'svelte';
-  import { cx } from '../../lib';
+  import { onDestroy } from "svelte";
 
-  let timeoutId = undefined;
+  $: animation = undefined;
+  $: timeoutId = undefined;
+  $: showFeedback = timeoutId !== undefined;
 
   onDestroy(() => {
     window.clearTimeout(timeoutId);
     timeoutId = undefined;
   });
-
-  $: showFeedback = timeoutId !== undefined;
 </script>
 
 <button
+  bind:this={ref}
   type="button"
-  class={className}
+  aria-live="polite"
+  class:bx--copy={true}
+  class:bx--copy-btn--animating={animation}
+  aria-label={animation ? feedback : undefined}
+  {...$$restProps}
+  class="{$$restProps.class}
+  {animation && `bx--copy-btn--${animation}`}"
   on:click
   on:click={() => {
-    timeoutId = window.setTimeout(() => {
-      showFeedback = undefined;
+    if (animation === 'fade-in') return;
+    animation = 'fade-in';
+    timeoutId = setTimeout(() => {
+      animation = 'fade-out';
     }, feedbackTimeout);
   }}
-  on:mouseover
-  on:mouseenter
-  on:mouseleave
-  {style}>
-  <slot />
-  <div
-    class={cx('--btn--copy__feedback', showFeedback && '--btn--copy__feedback--displayed')}
-    data-feedback={feedback} />
+  on:animationend
+  on:animationend={({ animationName }) => {
+    if (animationName === 'hide-feedback') {
+      animation = undefined;
+    }
+  }}>
+  <slot>
+    {#if animation}{feedback || $$restProps['aria-label']}{/if}
+  </slot>
+  <span
+    aria-hidden="true"
+    class:bx--assistive-text={true}
+    class:bx--copy-btn__feedback={true}>
+    {feedback}
+  </span>
 </button>