feat(users): add myth-auth to handle users crud + add admin gateway only accessible by login

- overwrite myth/auth config with castopod app needs
- create custom views for users authentication
- add admin area bootstrapped by admin controller
- shift podcast and episodes crud to admin area
- reorganize view layouts
- update docs for database migration
- add myth-auth to DEPENDENCIES.md

closes #11

app/Controllers/BaseController.php

@@ -1,7 +1,5 @@
 <?php
 
-namespace App\Controllers;
-
 /**
  * Class BaseController
  *
@@ -15,6 +13,8 @@ namespace App\Controllers;
  * @package CodeIgniter
  */
 
+namespace App\Controllers;
+
 use CodeIgniter\Controller;
 
 class BaseController extends Controller