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/flysystem/src/ProxyArrayAccessToProperties.php

@@ -0,0 +1,62 @@
+<?php
+
+declare(strict_types=1);
+
+namespace League\Flysystem;
+
+use RuntimeException;
+
+/**
+ * @internal
+ */
+trait ProxyArrayAccessToProperties
+{
+    private function formatPropertyName(string $offset): string
+    {
+        return str_replace('_', '', lcfirst(ucwords($offset, '_')));
+    }
+
+    /**
+     * @param mixed $offset
+     *
+     * @return bool
+     */
+    public function offsetExists($offset): bool
+    {
+        $property = $this->formatPropertyName((string) $offset);
+
+        return isset($this->{$property});
+    }
+
+    /**
+     * @param mixed $offset
+     *
+     * @return mixed
+     */
+    #[\ReturnTypeWillChange]
+    public function offsetGet($offset)
+    {
+        $property = $this->formatPropertyName((string) $offset);
+
+        return $this->{$property};
+    }
+
+    /**
+     * @param mixed $offset
+     * @param mixed $value
+     */
+    #[\ReturnTypeWillChange]
+    public function offsetSet($offset, $value): void
+    {
+        throw new RuntimeException('Properties can not be manipulated');
+    }
+
+    /**
+     * @param mixed $offset
+     */
+    #[\ReturnTypeWillChange]
+    public function offsetUnset($offset): void
+    {
+        throw new RuntimeException('Properties can not be manipulated');
+    }
+}