feat(ContextMenu/DropdownMenu): handle checkbox items type

Resolves #2144

docs/app/components/content/examples/dropdown-menu/DropdownMenuCheckboxItemsExample.vue

@@ -0,0 +1,46 @@
+<script setup lang="ts">
+const showBookmarks = ref(true)
+const showHistory = ref(false)
+const showDownloads = ref(false)
+
+const items = computed(() => [{
+  label: 'Interface',
+  icon: 'i-heroicons-window',
+  type: 'label' as const
+}, {
+  type: 'separator' as const
+}, {
+  label: 'Show Bookmarks',
+  icon: 'i-heroicons-bookmark',
+  type: 'checkbox' as const,
+  checked: showBookmarks.value,
+  onUpdateChecked(checked: boolean) {
+    showBookmarks.value = checked
+  },
+  onSelect(e?: Event) {
+    e?.preventDefault()
+  }
+}, {
+  label: 'Show History',
+  icon: 'i-heroicons-clock',
+  type: 'checkbox' as const,
+  checked: showHistory.value,
+  onUpdateChecked(checked: boolean) {
+    showHistory.value = checked
+  }
+}, {
+  label: 'Show Downloads',
+  icon: 'i-heroicons-arrow-down-on-square',
+  type: 'checkbox' as const,
+  checked: showDownloads.value,
+  onUpdateChecked(checked: boolean) {
+    showDownloads.value = checked
+  }
+}])
+</script>
+
+<template>
+  <UDropdownMenu :items="items" :content="{ align: 'start' }" class="w-48">
+    <UButton label="Open" color="neutral" variant="outline" icon="i-heroicons-bars-3" />
+  </UDropdownMenu>
+</template>