first commit on the UIShell

src/components/UIShell/UIShellNav/UIShellNavItem.svelte

@@ -0,0 +1,41 @@
+<script>
+  export let href = undefined;
+  export let text = undefined;
+  export let subMenu = undefined;
+
+  import { cx } from '../../../lib';
+  import UIShellSubmenu from './UIShellNavSubmenu.svelte';
+</script>
+
+{#if href}
+  <li>
+    <a
+      class={cx('--header__menu-item')}
+      role="menuitem"
+      tabindex="0"
+      on:click
+      on:mouseover
+      on:mouseenter
+      on:mouseleave
+      on:keyup
+      on:keydown
+      on:focus
+      on:blur
+      {href}>
+      <span class={cx('--text-truncate--end')}>{text}</span>
+    </a>
+  </li>
+{:else}
+  <UIShellSubmenu
+    {href}
+    {text}
+    {subMenu}
+    on:click
+    on:mouseover
+    on:mouseenter
+    on:mouseleave
+    on:keyup
+    on:keydown
+    on:focus
+    on:blur />
+{/if}