[1.2.x] Group by Field Widget

I am closing this application, since there haven't been replies in more than eight months and the application was open more than eleven months ago.
Feel free to re-open it, once the project has been changed basing on what reported in the last review.

Drupal 10 compatibility added, and coding standards applied.

Thank you for your contribution! I am going to update your account.

These are some recommended readings to help with excellent maintainership:

• Dries → ' post on Responsible maintainers
• Best practices for creating and maintaining projects →
• Maintaining a drupal.org project with Git →
• Commit messages - providing history and credit →
• Release naming conventions → .
• Helping maintainers in the issue queues →

You can find more contributors chatting on the Slack → #contribute channel. So, come hang out and stay involved → .
Thank you, also, for your patience with the review process.
Anyone is welcome to participate in the review process. Please consider reviewing other projects that are pending review → . I encourage you to learn more about that process and join the group of reviewers.

I thank all the reviewers.

Automatically closed - issue fixed for 2 weeks with no activity.