Build modified streamline images

The official image from streamline does not currently work for the arm64
platform. As a temporary measure, the source code and docker build scripts
have been lifted from the official images and are used to build locally.

Some additional modifications are made to reduce overall image size, these
are documented in docker/README.md

docker/streamline-src/vendor/symfony/http-kernel/HttpCache/Ssi.php

@@ -0,0 +1,86 @@
+<?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\HttpKernel\HttpCache;
+
+use Symfony\Component\HttpFoundation\Request;
+use Symfony\Component\HttpFoundation\Response;
+
+/**
+ * Ssi implements the SSI capabilities to Request and Response instances.
+ *
+ * @author Sebastian Krebs <krebs.seb@gmail.com>
+ */
+class Ssi extends AbstractSurrogate
+{
+    public function getName(): string
+    {
+        return 'ssi';
+    }
+
+    /**
+     * @return void
+     */
+    public function addSurrogateControl(Response $response)
+    {
+        if (str_contains($response->getContent(), '<!--#include')) {
+            $response->headers->set('Surrogate-Control', 'content="SSI/1.0"');
+        }
+    }
+
+    public function renderIncludeTag(string $uri, ?string $alt = null, bool $ignoreErrors = true, string $comment = ''): string
+    {
+        return sprintf('<!--#include virtual="%s" -->', $uri);
+    }
+
+    public function process(Request $request, Response $response): Response
+    {
+        $type = $response->headers->get('Content-Type');
+        if (empty($type)) {
+            $type = 'text/html';
+        }
+
+        $parts = explode(';', $type);
+        if (!\in_array($parts[0], $this->contentTypes)) {
+            return $response;
+        }
+
+        // we don't use a proper XML parser here as we can have SSI tags in a plain text response
+        $content = $response->getContent();
+        $boundary = self::generateBodyEvalBoundary();
+        $chunks = preg_split('#<!--\#include\s+(.*?)\s*-->#', $content, -1, \PREG_SPLIT_DELIM_CAPTURE);
+
+        $i = 1;
+        while (isset($chunks[$i])) {
+            $options = [];
+            preg_match_all('/(virtual)="([^"]*?)"/', $chunks[$i], $matches, \PREG_SET_ORDER);
+            foreach ($matches as $set) {
+                $options[$set[1]] = $set[2];
+            }
+
+            if (!isset($options['virtual'])) {
+                throw new \RuntimeException('Unable to process an SSI tag without a "virtual" attribute.');
+            }
+
+            $chunks[$i] = $boundary.$options['virtual']."\n\n\n";
+            $i += 2;
+        }
+        $content = $boundary.implode('', $chunks).$boundary;
+
+        $response->setContent($content);
+        $response->headers->set('X-Body-Eval', 'SSI');
+
+        // remove SSI/1.0 from the Surrogate-Control header
+        $this->removeFromControl($response);
+
+        return $response;
+    }
+}