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/guzzlehttp/guzzle/src/Handler/CurlHandler.php

@@ -0,0 +1,49 @@
+<?php
+
+namespace GuzzleHttp\Handler;
+
+use GuzzleHttp\Promise\PromiseInterface;
+use Psr\Http\Message\RequestInterface;
+
+/**
+ * HTTP handler that uses cURL easy handles as a transport layer.
+ *
+ * When using the CurlHandler, custom curl options can be specified as an
+ * associative array of curl option constants mapping to values in the
+ * **curl** key of the "client" key of the request.
+ *
+ * @final
+ */
+class CurlHandler
+{
+    /**
+     * @var CurlFactoryInterface
+     */
+    private $factory;
+
+    /**
+     * Accepts an associative array of options:
+     *
+     * - handle_factory: Optional curl factory used to create cURL handles.
+     *
+     * @param array{handle_factory?: ?CurlFactoryInterface} $options Array of options to use with the handler
+     */
+    public function __construct(array $options = [])
+    {
+        $this->factory = $options['handle_factory']
+            ?? new CurlFactory(3);
+    }
+
+    public function __invoke(RequestInterface $request, array $options): PromiseInterface
+    {
+        if (isset($options['delay'])) {
+            \usleep($options['delay'] * 1000);
+        }
+
+        $easy = $this->factory->create($request, $options);
+        \curl_exec($easy->handle);
+        $easy->errno = \curl_errno($easy->handle);
+
+        return CurlFactory::finish($this, $easy, $this->factory);
+    }
+}