Migrating pre 1.12 Android project

[ajini-sahaejana]

The flutter create templates for apps and plugins no longer create Android wrapping based on the v1 Android embedding as part of our gradual Android v1 embedding deprecation process.

Application projects using the v1 Android embedding are encouraged to migrate following the steps described in Upgrading pre 1.12 Android projects.

I have made all the above required changes to the repository so that there won't be the following warning in the console any more. :D

Warning
──────────────────────────────────────────────────────────────────────────────
Your Flutter application is created using an older version of the Android
embedding. It's being deprecated in favor of Android embedding v2. Follow the
steps at

https://flutter.dev/go/android-project-migration

to migrate your project.
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Launching lib\main.dart on sdk gphone x86 arm in debug mode...
Running Gradle task 'assembleDebug'...
√ Built build\app\outputs\flutter-apk\app-debug.apk.
Installing build\app\outputs\flutter-apk\app.apk...