[Bug] The text being edited when displayed in the IME is not underlined.

### Bug Description

Underline is not added to the text being edited when the IME is displayed.

iOS Memo app

AppFlowy

### How to Reproduce

Enter "あいうえお" on a Japanese keyboard

### Expected Behavior

Underline is added to the text being edited

### Operating System

iOS, Android

### AppFlowy Editor Version(s)

4.0.0

### Screenshots

_No response_

### Additional Context

https://api.flutter.dev/flutter/services/TextEditingValue/composing.html

Composing of TextEditingValue seems to be related.