MAPG-140 add UserConfirmation model and repository and adapt SignupController

src/Repository/UserConfirmationRepository.php

@@ -0,0 +1,28 @@
+<?php namespace MapGuesser\Repository;
+
+use MapGuesser\Database\Query\Select;
+use MapGuesser\PersistentData\Model\UserConfirmation;
+use MapGuesser\PersistentData\PersistentDataManager;
+
+class UserConfirmationRepository
+{
+    private PersistentDataManager $pdm;
+
+    public function __construct()
+    {
+        $this->pdm = new PersistentDataManager();
+    }
+
+    public function getById(int $userConfirmationId): ?UserConfirmation
+    {
+        return $this->pdm->selectFromDbById($userConfirmationId, UserConfirmation::class);
+    }
+
+    public function getByToken(string $token): ?UserConfirmation
+    {
+        $select = new Select(\Container::$dbConnection);
+        $select->where('token', '=', $token);
+
+        return $this->pdm->selectFromDb($select, UserConfirmation::class);
+    }
+}