feat(Button): loading-auto (#2198)

docs/app/components/content/examples/button/ButtonLoadingAutoExample.vue

@@ -0,0 +1,11 @@
+<script setup lang="ts">
+async function onClick() {
+  return new Promise<void>(res => setTimeout(res, 1000))
+}
+</script>
+
+<template>
+  <UButton loading-auto @click="onClick">
+    Button
+  </UButton>
+</template>