feat: Flutter example migration

[albertodev01]

Why?

I need to migrate the project in example/flutter_example to Flutter 3.0

What?

• Migrated code in example/flutter_example to Flutter 3.0
• Removed flutter_bloc and replaced with Flutter's built-in state management (InheritedWidget and notifier classes)
• Tests and goldens updates
• Added support to macOS, Linux and Windows
• Updates on the web build
• Navigator 2.0 implementation with Flutter's go_router

Types of Changes

• New feature (non-breaking change which adds functionality)
• General improvements (quality updates to improve the stability of the project)

Notes

yay

Checklist

• I have provided a description of the proposed changes.
• I added unit tests for all relevant code.
• I added golden tests for all UI changes.
• I added documentation for all relevant code.