Add Composer autoloading functions and PHPStan for testing

vendor/symfony/contracts/Translation/LocaleAwareInterface.php

@@ -0,0 +1,31 @@
+<?php
+
+/*
+ * This file is part of the Symfony package.
+ *
+ * (c) Fabien Potencier <fabien@symfony.com>
+ *
+ * For the full copyright and license information, please view the LICENSE
+ * file that was distributed with this source code.
+ */
+
+namespace Symfony\Contracts\Translation;
+
+interface LocaleAwareInterface
+{
+    /**
+     * Sets the current locale.
+     *
+     * @param string $locale The locale
+     *
+     * @throws \InvalidArgumentException If the locale contains invalid characters
+     */
+    public function setLocale($locale);
+
+    /**
+     * Returns the current locale.
+     *
+     * @return string The locale
+     */
+    public function getLocale();
+}