Add column information as table header for `flutter emulators` command.

**Before:**

```
2 available emulators:

Pixel_3_API_30   • Pixel 3 API 30   • Google • android
Resizable_API_33 • Resizable API 33 • Google • android

To run an emulator, run 'flutter emulators --launch <emulator id>'.
To create a new emulator, run 'flutter emulators --create [--name xyz]'.

You can find more information on managing emulators at the links below:
  https://developer.android.com/studio/run/managing-avds
  https://developer.android.com/studio/command-line/avdmanager
```

**After:**

```
2 available emulators:

Id               • Name             • Manufacturer • Platform

Pixel_3_API_30   • Pixel 3 API 30   • Google       • android
Resizable_API_33 • Resizable API 33 • Google       • android

To run an emulator, run 'flutter emulators --launch <emulator id>'.
To create a new emulator, run 'flutter emulators --create [--name xyz]'.

You can find more information on managing emulators at the links below:
  https://developer.android.com/studio/run/managing-avds
  https://developer.android.com/studio/command-line/avdmanager
```

fixes #140656