Repository: flutter
Issue: [image_picker] XFile return null mimeType on macOS
Labels: platform-ios,platform-mac,p: image_picker,package,a: desktop,team-ecosystem,P3,triaged-ecosystem

### Steps to reproduce

1 run the code on macos
2 pick a image
3 check the console output

### Expected results

print the image's mimeType

### Actual results

print null

### Code sample

<details open><summary>Code sample</summary>

```dart
import 'package:flutter/material.dart';
import 'package:image_picker/image_picker.dart';

void main() {
  runApp(const MyApp());
}

class MyApp extends StatelessWidget {
  const MyApp({super.key});

  @override
  Widget build(BuildContext context) {
    return const MaterialApp(
      title: 'Image Picker Demo',
      home: MyHomePage(),
    );
  }
}

class MyHomePage extends StatefulWidget {
  const MyHomePage({super.key});

  @override
  State<MyHomePage> createState() => _MyHomePageState();
}

class _MyHomePageState extends State<MyHomePage> {
  addPhoto() async {
    final ImagePicker picker = ImagePicker();
    final List<XFile> pickedFileList = await picker.pickMultiImage();
    for (XFile element in pickedFileList) {
      int length = await element.length();
      debugPrint('${length}');
      debugPrint('${element.mimeType}');
    }
  }

  @override
  Widget build(BuildContext context) {
    return Scaffold(
      body: ElevatedButton(
          onPressed: () {
            addPhoto();
          },
          child: Text('pick')),
    );
  }
}

```

</details>


### Screenshots or Video

<details open>
<summary>Screenshots / Video demonstration</summary>

[Upload media here]

</details>


### Logs

<details open><summary>Logs</summary>

```console
flutter: 661970
flutter: null
```

</details>


### Flutter Doctor output

<details open><summary>Doctor output</summary>

```console
[✓] Flutter (Channel stable, 3.19.0, on macOS 14.3.1 23D60 darwin-arm64, locale zh-Hans-CN)
    • Flutter version 3.19.0 on channel stable at /Users/cruvie/Documents/DevelopmentEnvironment/flutter
    • Upstream repository https://github.com/flutter/flutter.git
    • Framework revision bae5e49bc2 (4 weeks ago), 2024-02-13 17:46:18 -0800
    • Engine revision 04817c99c9
    • Dart version 3.3.0
    • DevTools version 2.31.1
    • Pub download mirror https://pub.flutter-io.cn
    • Flutter download mirror https://storage.flutter-io.cn

[!] Android toolchain - develop for Android devices (Android SDK version 34.0.0)
    • Android SDK at /Users/cruvie/Library/Android/sdk
    ✗ cmdline-tools component is missing
      Run `path/to/sdkmanager --install "cmdline-tools;latest"`
      See https://developer.android.com/studio/command-line for more details.
    ✗ Android license status unknown.
      Run `flutter doctor --android-licenses` to accept the SDK licenses.
      See https://flutter.dev/docs/get-started/install/macos#android-setup for more details.

[✓] Xcode - develop for iOS and macOS (Xcode 15.3)
    • Xcode at /Applications/Xcode.app/Contents/Developer
    • Build 15E204a
    • CocoaPods version 1.14.3

[✗] Chrome - develop for the web (Cannot find Chrome executable at /Applications/Google Chrome.app/Contents/MacOS/Google Chrome)
    ! Cannot find Chrome. Try setting CHROME_EXECUTABLE to a Chrome executable.

[!] Android Studio (not installed)
    • Android Studio not found; download from https://developer.android.com/studio/index.html
      (or visit https://flutter.dev/docs/get-started/install/macos#android-setup for detailed instructions).

[✓] IntelliJ IDEA Ultimate Edition (version 2023.3.4)
    • IntelliJ at /Users/cruvie/Applications/IntelliJ IDEA Ultimate.app
    • Flutter plugin version 78.3.1
    • Dart plugin version 233.13763.5

[✓] VS Code (version 1.86.2)
    • VS Code at /Applications/Visual Studio Code.app/Contents
    • Flutter extension version 3.84.0

[✓] Connected device (1 available)
    • macOS (desktop) • macos • darwin-arm64 • macOS 14.3.1 23D60 darwin-arm64

[✓] Network resources
    • All expected network resources are available.

! Doctor found issues in 3 categories.

```

</details>