refactor(modules): extract castopod parts into a modules/ folder for a scalable HMVC structure

- create Admin, Analytics, Auth, Fediverse and Install modules in the root modules/ folder
- rename
ActivityPub to Fediverse

modules/Admin/Controllers/HomeController.php

@@ -0,0 +1,22 @@
+<?php
+
+declare(strict_types=1);
+
+/**
+ * @copyright  2020 Podlibre
+ * @license    https://www.gnu.org/licenses/agpl-3.0.en.html AGPL3
+ * @link       https://castopod.org/
+ */
+
+namespace Modules\Admin\Controllers;
+
+use CodeIgniter\HTTP\RedirectResponse;
+
+class HomeController extends BaseController
+{
+    public function index(): RedirectResponse
+    {
+        session()->keepFlashdata('message');
+        return redirect()->route('podcast-list');
+    }
+}