add new getters to userrepository

src/Repository/UserRepository.php

@@ -22,6 +22,23 @@ class UserRepository implements IUserRepository
         return \Container::$persistentDataManager->selectFromDb($select, User::class);
     }
 
+    public function getByUsername(string $username): ?User
+    {
+        $select = new Select(\Container::$dbConnection);
+        $select->where('username', '=', $username);
+
+        return \Container::$persistentDataManager->selectFromDb($select, User::class);
+    }
+
+    public function getByEmailOrUsername(string $emailOrUsername): ?User
+    {
+        if (filter_var($emailOrUsername, FILTER_VALIDATE_EMAIL)) {
+            return $this->getByEmail($emailOrUsername);
+        }
+
+        return $this->getByUsername($emailOrUsername);
+    }
+
     public function getByGoogleSub(string $sub): ?User
     {
         $select = new Select(\Container::$dbConnection);