Expand Relations by dot

added new parsing logic for query attribute
so if user wants to expand the fields of a
relations ( many 2 one, one 2 one , and so)
it should add . to the name of the relation like
?expand=location,location.venue
that will expand the location venue.

Change-Id: I6c50d10e793f017da9146dbce5c5e86a631d9224

app/Repositories/Main/DoctrineGroupRepository.php

@@ -53,4 +53,14 @@ final class DoctrineGroupRepository
     {
        return Group::class;
     }
+
+
+    /**
+     * @param string $slug
+     * @return Group|null
+     */
+    public function getBySlug(string $slug): ?Group
+    {
+        return $this->findOneBy(['code'=>trim($slug)]);
+    }
 }