Migrate ECA GitHub validation to Quarkus

This is an MBO for Q1. The objective for this MBO is to migrate the webhook functionality for the Eclipse ECA Validation GitHub APP from Drupal (accounts.eclipse.org) to this project.

Also included are the validation pages such as https://accounts.eclipse.org/legal/eca/validation/126686. They need to be migrated to this application.

@malowe Can you please break down this initiative into smaller tasks or issues for everything that you think we will need to accomplish such as but not limited to deploying to production and defining a plan on how we are going to deal with backward compatibility, testing...?