Add normalization and denormalization for RollingDate

Introduce methods to normalize and recreate RollingDate objects, ensuring consistent serialization and deserialization. Includes corresponding tests for both cases with and without a pivot date.

src/Bundle/ChillMainBundle/Tests/Services/RollingDate/RollingDateTest.php

@@ -0,0 +1,45 @@
+<?php
+
+declare(strict_types=1);
+
+/*
+ * Chill is a software for social workers
+ *
+ * For the full copyright and license information, please view
+ * the LICENSE file that was distributed with this source code.
+ */
+
+namespace Chill\MainBundle\Tests\Services\RollingDate;
+
+use Chill\MainBundle\Service\RollingDate\RollingDate;
+use PHPUnit\Framework\TestCase;
+
+/**
+ * @internal
+ *
+ * @coversNothing
+ */
+class RollingDateTest extends TestCase
+{
+    public function testNormalizationDenormalizationProcessWithoutPivotDate(): void
+    {
+        $date = new RollingDate(RollingDate::T_YEAR_PREVIOUS_START);
+
+        $actual = RollingDate::fromNormalized($date->normalize());
+
+        self::assertEquals(RollingDate::T_YEAR_PREVIOUS_START, $actual->getRoll());
+        self::assertNull($actual->getFixedDate());
+        self::assertEquals($date->getPivotDate()->getTimestamp(), $actual->getPivotDate()->getTimestamp());
+    }
+
+    public function testNormalizationDenormalizationProcessWithPivotDate(): void
+    {
+        $date = new RollingDate(RollingDate::T_FIXED_DATE, $pivot = new \DateTimeImmutable('now'));
+
+        $actual = RollingDate::fromNormalized($date->normalize());
+
+        self::assertEquals(RollingDate::T_FIXED_DATE, $actual->getRoll());
+        self::assertEquals($pivot, $actual->getFixedDate());
+        self::assertEquals($date->getPivotDate()->getTimestamp(), $actual->getPivotDate()->getTimestamp());
+    }
+}