Update to the v2 Android Plugin

[dipu-bd]

When I try using this plugin in a flutter module project, it shows this warning during flutter pub get:

The plugin `pdf_flutter` is built using an older version of the Android plugin API which assumes that it's running in a full-Flutter environment. It may have undefined behaviors when Flutter is integrated into an existing app as a module.
The plugin can be updated to the v2 Android Plugin APIs by following https://flutter.dev/go/android-plugin-migration.

❯ flutter doctor

Doctor summary (to see all details, run flutter doctor -v):
[✓] Flutter (Channel stable, 1.22.4, on Linux, locale en_US.UTF-8)
 
[✓] Android toolchain - develop for Android devices (Android SDK version 30.0.2)
[!] Android Studio (not installed)
[✓] VS Code (version 1.51.1)
[✓] Connected device (1 available)

! Doctor found issues in 1 category.