Investigate support for FedCM

[joelabreo227]

Reference:

• https://developers.google.com/identity/gsi/web/guides/fedcm-migration
• https://github.com/rtCamp/scripbox.com/pull/441/files

  
  ### Tasks

• [x] TODO: Add initial acceptance criteria

  
  ### Acceptance Criteria

• Implement FedCM within the plugin to improve security and user experience.
• FedCM support should work alongside existing Google Sign-In implementation. Ensure migration is seamless for existing users without requiring them to reconfigure their settings.
• Plugin is compatible with all major browsers after migration.
• The authentication process does not add significant delays compared to the previous implementation.
• Documentation is updated as per the changes.