feat(component): add MultiSelect

Closes #19

src/components/MultiSelect/MultiSelect.Story.svelte

@@ -0,0 +1,41 @@
+<script>
+  import Layout from '../../internal/ui/Layout.svelte';
+  import Button from '../Button';
+  import MultiSelect from './MultiSelect.svelte';
+
+  let value = '';
+
+  let items = [
+    { id: 'option-0', text: 'Option 1' },
+    { id: 'option-1', text: 'Option 2' },
+    { id: 'option-2', text: 'Option 3' },
+    { id: 'option-3', text: 'Option 4' },
+    {
+      id: 'option-4',
+      text: 'An example option that is really long to show what should be done to handle long text'
+    }
+  ];
+
+  let selectedIds = [];
+</script>
+
+<Layout>
+  <div>
+    <Button
+      size="small"
+      on:click={() => {
+        selectedIds = selectedIds.length > 0 ? [] : [items[1].id, items[2].id];
+      }}>
+      {selectedIds.length > 0 ? 'Clear' : 'Set initial'} selected items
+    </Button>
+  </div>
+  <div style="width: 300px; margin-top: 2rem;">
+    <MultiSelect
+      {...$$props}
+      id="multiselect"
+      placeholder="Filter..."
+      bind:selectedIds
+      bind:items
+      bind:value />
+  </div>
+</Layout>