refactor(structured-list): make StructuredListWrapper default component

src/components/StructuredList/StructuredList.svelte

@@ -0,0 +1,39 @@
+<script>
+  let className = undefined;
+  export { className as class };
+  export let selected = undefined;
+  export let border = false;
+  export let selection = false;
+  export let style = undefined;
+
+  import { createEventDispatcher, setContext } from 'svelte';
+  import { writable } from 'svelte/store';
+  import { cx } from '../../lib';
+
+  const dispatch = createEventDispatcher();
+
+  let selectedValue = writable(selected);
+
+  setContext('StructuredListWrapper', {
+    selectedValue,
+    update: value => {
+      selectedValue.set(value);
+    }
+  });
+
+  $: selected = $selectedValue;
+  $: {
+    dispatch('change', $selectedValue);
+  }
+</script>
+
+<section
+  on:click
+  on:mouseover
+  on:mouseenter
+  on:mouseleave
+  aria-label={$$props['aria-label'] || 'Structured list section'}
+  class={cx('--structured-list', border && '--structured-list--border', selection && '--structured-list--selection', className)}
+  {style}>
+  <slot />
+</section>