Enable Attach only for modules

Thanks for the feedback! If your issue is related to the Flutter framework itself,
please open an issue at
[github.com/flutter/flutter](https://github.com/flutter/flutter/issues/new).

## Steps to Reproduce

After using Flutter Attach for debugging, I clicked on Stop button, but it still keeps enable. I have to restart Android Studio. It's quite inconvenient.
Pls help to fix that!

Thanks!

## Version info

Please paste the output of running `flutter doctor -v` here (available from the command
line or from `Tools > Flutter > Flutter Doctor`). It will provide the version of the
Flutter framework as well as of the IntelliJ plugin.

```
╔════════════════════════════════════════════════════════════════════════════╗
║ A new version of Flutter is available! ║
║ ║
║ To update to the latest version, run "flutter upgrade". ║
╚════════════════════════════════════════════════════════════════════════════╝

[✓] Flutter (Channel stable, 2.0.6, on macOS 11.2.3 20D91 darwin-x64, locale en-VN)
• Flutter version 2.0.6 at /Users/huynq/Documents/GitHub/flutter
• Framework revision 1d9032c7e1 (5 weeks ago), 2021-04-29 17:37:58 -0700
• Engine revision 05e680e202
• Dart version 2.12.3

[✓] Android toolchain - develop for Android devices (Android SDK version 30.0.3)
• Android SDK at /Users/huynq/Library/Android/sdk
• Platform android-30, build-tools 30.0.3
• ANDROID_HOME = /Users/huynq/Library/Android/sdk
• Java binary at: /Users/huynq/Library/Application Support/JetBrains/Toolbox/apps/AndroidStudio/ch-0/201.7042882/Android
Studio.app/Contents/jre/jdk/Contents/Home/bin/java
• Java version OpenJDK Runtime Environment (build 1.8.0_242-release-1644-b3-6915495)
• All Android licenses accepted.

[✓] Xcode - develop for iOS and macOS
• Xcode at /Applications/Xcode.app/Contents/Developer
• Xcode 12.5, Build version 12E262
• CocoaPods version 1.10.1

[✓] Chrome - develop for the web
• Chrome at /Applications/Google Chrome.app/Contents/MacOS/Google Chrome

[✓] Android Studio (version 4.1)
• Android Studio at /Applications/Android Studio.app/Contents
• Flutter plugin can be installed from:
🔨 https://plugins.jetbrains.com/plugin/9212-flutter
• Dart plugin can be installed from:
🔨 https://plugins.jetbrains.com/plugin/6351-dart
• Java version OpenJDK Runtime Environment (build 1.8.0_242-release-1644-b3-6915495)

[✓] Android Studio (version 4.1)
• Android Studio at /Users/huynq/Library/Application Support/JetBrains/Toolbox/apps/AndroidStudio/ch-0/201.7042882/Android Studio.app/Contents
• Flutter plugin can be installed from:
🔨 https://plugins.jetbrains.com/plugin/9212-flutter
• Dart plugin can be installed from:
🔨 https://plugins.jetbrains.com/plugin/6351-dart
• Java version OpenJDK Runtime Environment (build 1.8.0_242-release-1644-b3-6915495)

[✓] Android Studio
• Android Studio at /Users/huynq/Library/Application Support/JetBrains/Toolbox/apps/AndroidStudio/ch-1/203.7185775/Android Studio
Preview.app/Contents
• Flutter plugin can be installed from:
🔨 https://plugins.jetbrains.com/plugin/9212-flutter
• Dart plugin can be installed from:
🔨 https://plugins.jetbrains.com/plugin/6351-dart
• Java version OpenJDK Runtime Environment (build 11.0.8+10-b944.6842174)

[✓] IntelliJ IDEA Community Edition (version 2020.3.3)
• IntelliJ at /Applications/IntelliJ IDEA CE.app
• Flutter plugin can be installed from:
🔨 https://plugins.jetbrains.com/plugin/9212-flutter
• Dart plugin can be installed from:
🔨 https://plugins.jetbrains.com/plugin/6351-dart

[✓] VS Code (version 1.56.2)
• VS Code at /Applications/Visual Studio Code.app/Contents
• Flutter extension version 3.22.0

[✓] Connected device (1 available)
• Chrome (web) • chrome • web-javascript • Google Chrome 91.0.4472.77

• No issues found!
```