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/Context.php

@@ -0,0 +1,51 @@
+<?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;
+
+
+final class Context
+{
+	public bool $skipDefaults = false;
+
+	/** @var string[] */
+	public array $path = [];
+
+	public bool $isKey = false;
+
+	/** @var Message[] */
+	public array $errors = [];
+
+	/** @var Message[] */
+	public array $warnings = [];
+
+	/** @var array[] */
+	public array $dynamics = [];
+
+
+	public function addError(string $message, string $code, array $variables = []): Message
+	{
+		$variables['isKey'] = $this->isKey;
+		return $this->errors[] = new Message($message, $code, $this->path, $variables);
+	}
+
+
+	public function addWarning(string $message, string $code, array $variables = []): Message
+	{
+		return $this->warnings[] = new Message($message, $code, $this->path, $variables);
+	}
+
+
+	/** @return \Closure(): bool */
+	public function createChecker(): \Closure
+	{
+		$count = count($this->errors);
+		return fn(): bool => $count === count($this->errors);
+	}
+}