解决 `flutter doctor` 错误 Dart plugin not installed; this adds Dart specific functionality

如果你使用的是 Mac 苹果电脑，而且使用的 Android Studio 是 4.1 以上的版本，那么，在运行 flutter doctor 的时候可能会出现下面的警告

Doctor summary (to see all details, run flutter doctor -v):
[✓] Flutter (Channel stable, 1.22.4, on Mac OS X 10.15.7 19H15 darwin-x64, locale zh-Hans-CN)
[✓] Android toolchain - develop for Android devices (Android SDK version 29.0.3)
[✓] Xcode - develop for iOS and macOS (Xcode 12.2)
[!] Android Studio (version 4.1)
    ✗ Flutter plugin not installed; this adds Flutter specific functionality.
    ✗ Dart plugin not installed; this adds Dart specific functionality.

[!] Connected device                          
    ! No devices available

原因是 Android Studio 4.1 以上的插件目录变更了，你需要做的就是运行下面的命令

ln -s ~/Library/Application\ Support/Google/AndroidStudio4.1/plugins ~/Library/Application\ Support/AndroidStudio4.1

然后重新运行一下 flutter doctor 就可以了

Doctor summary (to see all details, run flutter doctor -v):
[✓] Flutter (Channel stable, 1.22.4, on Mac OS X 10.15.7 19H15 darwin-x64, locale zh-Hans-CN)

[✓] Android toolchain - develop for Android devices (Android SDK version 29.0.3)
[✓] Xcode - develop for iOS and macOS (Xcode 12.2)
[✓] Android Studio (version 4.1)

[✓] Connected device (1 available)            

• No issues found!