refactor(watermark): move to script setup

[eiinu]

这个 PR 做了什么? (简要描述所做更改)

这个 PR 是什么类型? (至少选择一个)

• [ ] feat: 新特性提交
• [ ] fix: bug 修复
• [x] docs: 文档改进
• [ ] style: 组件样式/交互改进
• [x] type: 类型定义更新
• [ ] perf: 性能、包体积优化
• [x] refactor: 代码重构、代码风格优化
• [ ] test: 测试用例
• [ ] chore(deps): 依赖升级
• [ ] chore(demo): 演示代码改进
• [ ] chore(locale): 国际化改进
• [ ] chore: 其他改动（是关于什么的改动？）

这个 PR 涉及以下平台:

• [x] NutUI H5 @nutui/nutui
• [x] NutUI Taro @nutui/nutui-taro

这个 PR 是否已自测:

• [x] 自测 Vite 脚手架使用 测试仓库
• [x] 自测 Taro 脚手架使用小程序 & Taro-H5 测试仓库

[codecov[bot]]

Codecov Report

Attention: Patch coverage is 91.11111% with 12 lines in your changes are missing coverage. Please review.

Project coverage is 84.01%. Comparing base (d83f94c) to head (43e6ceb).

Files	Patch %	Lines
src/packages/__VUE/watermark/watermark.vue	90.16%	12 Missing :warning:

Additional details and impacted files

```diff @@ Coverage Diff @@ ## v4 #3066 +/- ## ========================================== + Coverage 83.99% 84.01% +0.01% ========================================== Files 224 225 +1 Lines 23018 22953 -65 Branches 2482 2484 +2 ========================================== - Hits 19335 19284 -51 + Misses 3665 3651 -14 Partials 18 18 ```

:umbrella: View full report in Codecov by Sentry.
:loudspeaker: Have feedback on the report? Share it here.