Rename/move directory won't change import

Manual search and replace currently required after renaming library directory.
Please add support for automatic refactor of imports.

Version info

```
[✓] Flutter (Channel beta, v1.12.13+hotfix.6, on Mac OS X 10.15.2 19C57, locale en-IL)
• Flutter version 1.12.13+hotfix.6 at /usr/local/lib/flutter
• Framework revision 18cd7a3601 (5 weeks ago), 2019-12-11 06:35:39 -0800
• Engine revision 2994f7e1e6
• Dart version 2.7.0

[✓] Android toolchain - develop for Android devices (Android SDK version 28.0.3)
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• Platform android-28, build-tools 28.0.3
• ANDROID_HOME = /Users/sasha/Library/Android/sdk
• ANDROID_SDK_ROOT = /Users/sasha/Library/Android/sdk
• Java binary at: /Applications/Android Studio.app/Contents/jre/jdk/Contents/Home/bin/java
• Java version OpenJDK Runtime Environment (build 1.8.0_202-release-1483-b49-5587405)
• All Android licenses accepted.

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• Xcode at /Applications/Xcode.app/Contents/Developer
• Xcode 11.3, Build version 11C29
• CocoaPods version 1.8.4

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[✓] Android Studio (version 3.5)
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• Flutter plugin version 42.1.1
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• Java version OpenJDK Runtime Environment (build 1.8.0_202-release-1483-b49-5587405)

[✓] IntelliJ IDEA Community Edition (version 2019.3.1)
• IntelliJ at /Applications/IntelliJ IDEA CE.app
• Flutter plugin version 42.1.4
• Dart plugin version 193.5731

[✓] VS Code (version 1.41.1)
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[✓] Connected device (3 available)
• iPhone 11 Pro Max • D06766C9-E399-4AEF-B840-D9F00FF661EE • ios • com.apple.CoreSimulator.SimRuntime.iOS-13-3 (simulator)
• Chrome • chrome • web-javascript • Google Chrome 79.0.3945.117
• Web Server • web-server • web-javascript • Flutter Tools

• No issues found!
```