Move to Symfony Flex

The structure changed completely.
Bundles are gone. Everything is flatten in the folder `src`.
I separated import & api controllers to avoid _pollution_ in the main controller folder.

tests/WallabagApiTestCase.php

@@ -0,0 +1,79 @@
+<?php
+
+namespace App\Tests;
+
+use App\Entity\User;
+use Doctrine\ORM\EntityManagerInterface;
+use FOS\UserBundle\Model\UserInterface;
+use FOS\UserBundle\Model\UserManager;
+use FOS\UserBundle\Security\LoginManager;
+use Symfony\Bundle\FrameworkBundle\Client;
+use Symfony\Bundle\FrameworkBundle\Test\WebTestCase;
+use Symfony\Component\BrowserKit\Cookie;
+use Symfony\Component\HttpFoundation\Session\SessionInterface;
+use Symfony\Component\Security\Core\Authentication\Token\Storage\TokenStorageInterface;
+
+abstract class WallabagApiTestCase extends WebTestCase
+{
+    /**
+     * @var Client
+     */
+    protected $client = null;
+
+    /**
+     * @var UserInterface
+     */
+    protected $user;
+
+    protected function setUp(): void
+    {
+        parent::setUp();
+        $this->client = $this->createAuthorizedClient();
+    }
+
+    /**
+     * @return Client
+     */
+    protected function createAuthorizedClient()
+    {
+        $client = static::createClient();
+        $container = $client->getContainer();
+
+        /** @var UserManager $userManager */
+        $userManager = $container->get('fos_user.user_manager.test');
+        /** @var LoginManager $loginManager */
+        $loginManager = $container->get('fos_user.security.login_manager.test');
+        $firewallName = $container->getParameter('fos_user.firewall_name');
+
+        $this->user = $userManager->findUserBy(['username' => 'admin']);
+        $loginManager->logInUser($firewallName, $this->user);
+
+        // save the login token into the session and put it in a cookie
+        $container->get(SessionInterface::class)->set('_security_' . $firewallName, serialize($container->get(TokenStorageInterface::class)->getToken()));
+        $container->get(SessionInterface::class)->save();
+
+        $session = $container->get(SessionInterface::class);
+        $client->getCookieJar()->set(new Cookie($session->getName(), $session->getId()));
+
+        return $client;
+    }
+
+    /**
+     * Return the ID for the user admin.
+     * Used because on heavy testing we don't want to re-create the database on each run.
+     * Which means "admin" user won't have id 1 all the time.
+     *
+     * @param string $username
+     *
+     * @return int
+     */
+    protected function getUserId($username = 'admin')
+    {
+        return $this->client
+            ->getContainer()
+            ->get(EntityManagerInterface::class)
+            ->getRepository(User::class)
+            ->findOneByUserName($username)
+            ->getId();
+    }
+}