added database driven system configurations with admin screen (#647)

tests/Configuration/TestConfigLoader.php

@@ -0,0 +1,35 @@
+<?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\Configuration;
+
+use App\Configuration\ConfigLoaderInterface;
+use App\Entity\Configuration;
+
+/**
+ * @covers \App\Configuration\FormConfiguration
+ */
+class TestConfigLoader implements ConfigLoaderInterface
+{
+    private $configs = [];
+
+    public function __construct(array $configs)
+    {
+        $this->configs = $configs;
+    }
+
+    /**
+     * @param null|string $prefix
+     * @return Configuration[]
+     */
+    public function getConfiguration(?string $prefix = null): array
+    {
+        return $this->configs;
+    }
+}