feat: api endpoints and xml sync for contingents data

tests/Service/BookingEditDraftManagerMutabilityTest.php

@@ -13,9 +13,9 @@ use App\Entity\User;
 use App\Form\Model\BookingDto;
 use App\Form\Model\ParticipantDto;
 use App\Repository\BookingEditDraftRepository;
+use App\Service\BookingChangeTracker;
 use App\Service\BookingEditDraftManager;
 use App\Service\BookingEditDraftMerger;
-use App\Service\BookingChangeTracker;
 use Doctrine\ORM\EntityManagerInterface;
 use PHPUnit\Framework\TestCase;
 use Psr\Log\NullLogger;