feat: Themes (#257)

* feat: add trait to unify get by id or slug logic

* feat: add Theme resource

* fix: categories and themes

* feat: update api docs for projects to themes relationship

* feat: update doctrine relationship of projects to themes

* feat: add v3 categories to v4 themes pumping during projects pumping

src/Repository/ThemeRepository.php

@@ -0,0 +1,45 @@
+<?php
+
+namespace App\Repository;
+
+use App\Entity\Theme;
+use Doctrine\Bundle\DoctrineBundle\Repository\ServiceEntityRepository;
+use Doctrine\Persistence\ManagerRegistry;
+
+/**
+ * @extends ServiceEntityRepository<Theme>
+ */
+class ThemeRepository extends ServiceEntityRepository
+{
+    use FindByIdOrSlugTrait;
+
+    public function __construct(ManagerRegistry $registry)
+    {
+        parent::__construct($registry, Theme::class);
+    }
+
+    //    /**
+    //     * @return Theme[] Returns an array of Theme objects
+    //     */
+    //    public function findByExampleField($value): array
+    //    {
+    //        return $this->createQueryBuilder('t')
+    //            ->andWhere('t.exampleField = :val')
+    //            ->setParameter('val', $value)
+    //            ->orderBy('t.id', 'ASC')
+    //            ->setMaxResults(10)
+    //            ->getQuery()
+    //            ->getResult()
+    //        ;
+    //    }
+
+    //    public function findOneBySomeField($value): ?Theme
+    //    {
+    //        return $this->createQueryBuilder('t')
+    //            ->andWhere('t.exampleField = :val')
+    //            ->setParameter('val', $value)
+    //            ->getQuery()
+    //            ->getOneOrNullResult()
+    //        ;
+    //    }
+}