🐛[BUG] ProFormFields的readonly属性优先级没有ProForm的优先级高

提问前先看看：

https://github.com/ryanhanwu/How-To-Ask-Questions-The-Smart-Way/blob/main/README-zh_CN.md

### 🐛 bug 描述

ProFormFields的readonly属性优先级没有ProForm的优先级高，按理说应该子组件的优先级更高才是，有些场景需要个别子表单组件不使用readonly，需要能覆盖ProForm的readonly配置。

### 📷 复现步骤

### 🏞 期望结果

### 💻 复现代码

### © 版本信息

- ProComponents 版本: [e.g. 4.0.0]
- umi 版本
- 浏览器环境
- 开发环境 [e.g. mac OS]

### 🚑 其他信息

Start by locating the ProForm and ProFormFields entry points and trace how their readonly properties are combined. Reproduce the reported priority behavior with a parent ProForm and an individual ProFormFields child, then verify that the child can override the parent setting.

Written by the indexing model from the issue text.