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/CacheWarmer/CacheWarmerInterface.php

@@ -0,0 +1,32 @@
+<?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\CacheWarmer;
+
+/**
+ * Interface for classes able to warm up the cache.
+ *
+ * @author Fabien Potencier <fabien@symfony.com>
+ */
+interface CacheWarmerInterface extends WarmableInterface
+{
+    /**
+     * Checks whether this warmer is optional or not.
+     *
+     * Optional warmers can be ignored on certain conditions.
+     *
+     * A warmer should return true if the cache can be
+     * generated incrementally and on-demand.
+     *
+     * @return bool
+     */
+    public function isOptional();
+}