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/doctrine/event-manager/src/EventArgs.php

@@ -0,0 +1,37 @@
+<?php
+
+declare(strict_types=1);
+
+namespace Doctrine\Common;
+
+/**
+ * EventArgs is the base class for classes containing event data.
+ *
+ * This class contains no event data. It is used by events that do not pass state
+ * information to an event handler when an event is raised. The single empty EventArgs
+ * instance can be obtained through {@link getEmptyInstance}.
+ */
+class EventArgs
+{
+    /**
+     * Single instance of EventArgs.
+     */
+    private static EventArgs|null $emptyEventArgsInstance = null;
+
+    /**
+     * Gets the single, empty and immutable EventArgs instance.
+     *
+     * This instance will be used when events are dispatched without any parameter,
+     * like this: EventManager::dispatchEvent('eventname');
+     *
+     * The benefit from this is that only one empty instance is instantiated and shared
+     * (otherwise there would be instances for every dispatched in the abovementioned form).
+     *
+     * @link https://msdn.microsoft.com/en-us/library/system.eventargs.aspx
+     * @see EventManager::dispatchEvent
+     */
+    public static function getEmptyInstance(): EventArgs
+    {
+        return self::$emptyEventArgsInstance ??= new EventArgs();
+    }
+}