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/Encoder/Base64MimeHeaderEncoder.php

@@ -1,43 +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\Encoder;
-
-/**
- * @author Chris Corbyn
- */
-final class Base64MimeHeaderEncoder extends Base64Encoder implements MimeHeaderEncoderInterface
-{
-    public function getName(): string
-    {
-        return 'B';
-    }
-
-    /**
-     * Takes an unencoded string and produces a Base64 encoded string from it.
-     *
-     * If the charset is iso-2022-jp, it uses mb_encode_mimeheader instead of
-     * default encodeString, otherwise pass to the parent method.
-     */
-    public function encodeString(string $string, ?string $charset = 'utf-8', int $firstLineOffset = 0, int $maxLineLength = 0): string
-    {
-        if ('iso-2022-jp' === strtolower($charset)) {
-            $old = mb_internal_encoding();
-            mb_internal_encoding('utf-8');
-            $newstring = mb_encode_mimeheader($string, 'iso-2022-jp', $this->getName(), "\r\n");
-            mb_internal_encoding($old);
-
-            return $newstring;
-        }
-
-        return parent::encodeString($string, $charset, $firstLineOffset, $maxLineLength);
-    }
-}