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/league/config/src/ConfigurationInterface.php

@@ -0,0 +1,46 @@
+<?php
+
+declare(strict_types=1);
+
+/*
+ * This file is part of the league/config package.
+ *
+ * (c) Colin O'Dell <colinodell@gmail.com>
+ *
+ * For the full copyright and license information, please view the LICENSE
+ * file that was distributed with this source code.
+ */
+
+namespace League\Config;
+
+use League\Config\Exception\UnknownOptionException;
+use League\Config\Exception\ValidationException;
+
+/**
+ * Interface for reading configuration values
+ */
+interface ConfigurationInterface
+{
+    /**
+     * @param string $key Configuration option path/key
+     *
+     * @psalm-param non-empty-string $key
+     *
+     * @return mixed
+     *
+     * @throws ValidationException if the schema failed to validate the given input
+     * @throws UnknownOptionException if the requested key does not exist or is malformed
+     */
+    public function get(string $key);
+
+    /**
+     * @param string $key Configuration option path/key
+     *
+     * @psalm-param non-empty-string $key
+     *
+     * @return bool Whether the given option exists
+     *
+     * @throws ValidationException if the schema failed to validate the given input
+     */
+    public function exists(string $key): bool;
+}