[bug] Using plugin-dialog and plugin-fs to write file on iOS is ineffective.

[nashaofu]

Replicate the code：https://github.com/shell360/tauri-issue
The replication steps：

1. git clone https://github.com/shell360/tauri-issue.git
2. cd tauri-issue && pnpm install
3. run pnpm tauri ios dev，And select the iOS simulator.
4. click save file button
5. When checking the file in iOS file management, it was found that the content was not successfully written.

import { useCallback, useState } from 'react'
import { save, open } from '@tauri-apps/plugin-dialog'
import { writeFile, readFile } from '@tauri-apps/plugin-fs'

function App() {
  const onSave = useCallback(async () => {
    const path = await save()
    if (!path) {
      return
    }

    let encoder = new TextEncoder()
    let data = encoder.encode('Hello World')
    await writeFile(path, data) // The content was not successfully written.
  }, [])

  const onOpen = useCallback(async () => {
    const path = await open()
    if (!path) {
      return
    }

    let content = await readFile(path)
    console.log(content)
  }, [])
  
  return (
    <main className="container">
      <button onClick={onSave}>save file</button>
      <button onClick={onOpen}>open file</button>
    </main>
  )
}

export default App