string字段无法发送带格式的多行文本

### Describe the bug

在postman和apifox等中，都可以post的form-data，给字段赋值多行格式文本（比如python代码段），发送成功。
而postcat填入到表单中后，格式丢失，会变成单行

### Environment

- 版本: 0.5.1
- Electron: 22.1.0
- Chromium: 108.0.5359.179
- Node.js: 16.17.1
- V8: 10.8.168.25-electron.0
- OS: Windows_NT x64 10.0.19044
- 平台: Electron

Reproduce the issue in Postcat 0.5.1 by sending a form-data field containing multiline text such as Python code. Compare the resulting request with Postman or Apifox, then verify that the line breaks are preserved in the sent field. Done means multiline formatting survives the form-data submission.

Written by the indexing model from the issue text.