Import latest app updates from streamline

An updated set of source files and initialization was provided by streamline to
address issues observed during initial testing. These files have been updated in
order to generate a new set of app images.

docker/streamline-src/vendor/symfony/mime/DraftEmail.php

@@ -1,45 +0,0 @@
-<?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\Component\Mime;
-
-use Symfony\Component\Mime\Header\Headers;
-use Symfony\Component\Mime\Part\AbstractPart;
-
-/**
- * @author Kevin Bond <kevinbond@gmail.com>
- */
-class DraftEmail extends Email
-{
-    public function __construct(?Headers $headers = null, ?AbstractPart $body = null)
-    {
-        parent::__construct($headers, $body);
-
-        $this->getHeaders()->addTextHeader('X-Unsent', '1');
-    }
-
-    /**
-     * Override default behavior as draft emails do not require From/Sender/Date/Message-ID headers.
-     * These are added by the client that actually sends the email.
-     */
-    public function getPreparedHeaders(): Headers
-    {
-        $headers = clone $this->getHeaders();
-
-        if (!$headers->has('MIME-Version')) {
-            $headers->addTextHeader('MIME-Version', '1.0');
-        }
-
-        $headers->remove('Bcc');
-
-        return $headers;
-    }
-}