performance improvements (#2329)

* remove work from constructor
* refactor twig extensions
* upgrade theme
* replace sub-request with direct template rendering

tests/Twig/Runtime/ExporterExtensionTest.php

@@ -0,0 +1,33 @@
+<?php
+
+/*
+ * This file is part of the Kimai time-tracking app.
+ *
+ * For the full copyright and license information, please view the LICENSE
+ * file that was distributed with this source code.
+ */
+
+namespace App\Tests\Twig\Runtime;
+
+use App\Export\ServiceExport;
+use App\Twig\Runtime\ExporterExtension;
+use PHPUnit\Framework\TestCase;
+
+/**
+ * @covers \App\Twig\Runtime\ExporterExtension
+ */
+class ExporterExtensionTest extends TestCase
+{
+    protected function getSut(): ExporterExtension
+    {
+        $service = new ServiceExport();
+
+        return new ExporterExtension($service);
+    }
+
+    public function testGetExporter()
+    {
+        $sut = $this->getSut();
+        self::assertEquals([], $sut->getTimesheetExporter());
+    }
+}