Started using OneLogin SAML lib directly

- Aligned and formatted config options.
- Provided way to override onelogin lib options if required.
- Added endpoints in core bookstack routes.
- Provided way to debug details provided by idp and formatted by
bookstack.
- Started on test work
- Handled case of email address already in use.

app/Http/Kernel.php

@@ -39,11 +39,6 @@ class Kernel extends HttpKernel
             'throttle:60,1',
             'bindings',
         ],
-        'saml' => [
-            \BookStack\Http\Middleware\EncryptCookies::class,
-            \Illuminate\Cookie\Middleware\AddQueuedCookiesToResponse::class,
-            \Illuminate\Session\Middleware\StartSession::class,
-        ],
     ];
 
     /**