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/nette/schema/src/Schema/ValidationException.php

@@ -0,0 +1,55 @@
+<?php
+
+/**
+ * This file is part of the Nette Framework (https://nette.org)
+ * Copyright (c) 2004 David Grudl (https://davidgrudl.com)
+ */
+
+declare(strict_types=1);
+
+namespace Nette\Schema;
+
+use Nette;
+
+
+/**
+ * Validation error.
+ */
+class ValidationException extends Nette\InvalidStateException
+{
+	/** @var Message[] */
+	private array $messages;
+
+
+	/**
+	 * @param  Message[]  $messages
+	 */
+	public function __construct(?string $message, array $messages = [])
+	{
+		parent::__construct($message ?: $messages[0]->toString());
+		$this->messages = $messages;
+	}
+
+
+	/**
+	 * @return string[]
+	 */
+	public function getMessages(): array
+	{
+		$res = [];
+		foreach ($this->messages as $message) {
+			$res[] = $message->toString();
+		}
+
+		return $res;
+	}
+
+
+	/**
+	 * @return Message[]
+	 */
+	public function getMessageObjects(): array
+	{
+		return $this->messages;
+	}
+}