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

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

@@ -0,0 +1,23 @@
+<script setup lang="ts">
+const state = reactive({ fullName: '' })
+
+async function onSubmit() {
+  return new Promise<void>(res => setTimeout(res, 1000))
+}
+
+async function validate(data: Partial<typeof state>) {
+  if (!data.fullName?.length) return [{ name: 'fullName', message: 'Required' }]
+  return []
+}
+</script>
+
+<template>
+  <UForm :state="state" :validate="validate" @submit="onSubmit">
+    <UFormField name="fullName" label="Full name">
+      <UInput v-model="state.fullName" />
+    </UFormField>
+    <UButton type="submit" class="mt-2" loading-auto>
+      Submit
+    </UButton>
+  </UForm>
+</template>