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/Base64ContentEncoder.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\Encoder;
-
-use Symfony\Component\Mime\Exception\RuntimeException;
-
-/**
- * @author Fabien Potencier <fabien@symfony.com>
- */
-final class Base64ContentEncoder extends Base64Encoder implements ContentEncoderInterface
-{
-    public function encodeByteStream($stream, int $maxLineLength = 0): iterable
-    {
-        if (!\is_resource($stream)) {
-            throw new \TypeError(sprintf('Method "%s" takes a stream as a first argument.', __METHOD__));
-        }
-
-        $filter = stream_filter_append($stream, 'convert.base64-encode', \STREAM_FILTER_READ, [
-            'line-length' => 0 >= $maxLineLength || 76 < $maxLineLength ? 76 : $maxLineLength,
-            'line-break-chars' => "\r\n",
-        ]);
-        if (!\is_resource($filter)) {
-            throw new RuntimeException('Unable to set the base64 content encoder to the filter.');
-        }
-
-        while (!feof($stream)) {
-            yield fread($stream, 16372);
-        }
-        stream_filter_remove($filter);
-    }
-
-    public function getName(): string
-    {
-        return 'base64';
-    }
-}