chore(@vben/playground): add a clipboard example (#4133)

* chore(@vben/playground): 增加剪切板示例

* chore: rm unuse code

playground/src/views/demos/features/clipboard/index.vue

@@ -0,0 +1,23 @@
+<script setup lang="ts">
+import { ref } from 'vue';
+
+import { Page } from '@vben/common-ui';
+
+import { useClipboard } from '@vueuse/core';
+import { Button, Input } from 'ant-design-vue';
+
+const source = ref('Hello');
+const { copy, text } = useClipboard({ source });
+</script>
+
+<template>
+  <Page title="剪切板示例">
+    <p class="mb-3">
+      Current copied: <code>{{ text || 'none' }}</code>
+    </p>
+    <Input.Group class="flex">
+      <Input v-model:value="source" placeholder="请输入" />
+      <Button type="primary" @click="copy(source)"> Copy </Button>
+    </Input.Group>
+  </Page>
+</template>