feat: Implement authentication with Apple

[fonkamloic]

Description

We are looking to implement authentication with Apple as an additional method for our users to sign in to our app.

The goal of this issue is to integrate Apple's authentication SDK into our app and allow users to sign in using their Apple ID. We will also need to handle the necessary user data and token management.

Tasks

• Research and evaluate the best practice for integrating Apple's authentication SDK into a Flutter app.
• Implement the necessary changes in the app's codebase to support Apple authentication.
• Test the implementation on both iOS and Android platforms.
• Update the app's privacy policy and terms of service to reflect the use of Apple authentication.

Acceptance Criteria

• The app should allow users to sign in using their Apple ID.
• User data and tokens are properly managed and stored.
• The app should work correctly on iOS platforms.
• The app's privacy policy and terms of service are updated to reflect the use of Apple authentication.

Additional Notes

Please make sure to use the latest version of Apple's authentication SDK.
This issue should not affect the existing authentication methods.
The implementation should be done in a way that it can be easily updated in the future.

References

https://developer.apple.com/documentation/sign_in_with_apple/
https://flutter.dev/docs/cookbook/networking/authentication