feat(components): add StructuredList

Closes #27

src/components/StructuredList/StructuredListInput.svelte

@@ -0,0 +1,37 @@
+<script>
+  let className = undefined;
+  export { className as class };
+  export let id = Math.random();
+  export let value = 'value';
+  export let title = 'title';
+  export let name = '';
+  export let checked = false;
+  export let style = undefined;
+
+  import { getContext } from 'svelte';
+  import { cx } from '../../lib';
+
+  const _class = cx('--structured-list-input', className);
+
+  const { selected, update } = getContext('StructuredListWrapper');
+
+  if (checked) {
+    update(value);
+  }
+
+  $: checked = $selected === value;
+</script>
+
+<input
+  type="radio"
+  tabindex="-1"
+  class={_class}
+  on:change={() => {
+    update(value);
+  }}
+  {value}
+  {name}
+  {title}
+  {style}
+  {id}
+  {checked} />