添加屏幕适配相关的代码与第三方库。

适配设备安全区域的第三方库[react-native-safearea-view](https://github.com/react-community/react-native-safe-area-view)


安装依赖
```
yarn add react-native-safe-area-view
```

使用

```js
import SafeAreaView from 'react-native-safe-area-view'

<SafeAreaView>
{//...}
</SafeAreaView>
```