Abstract factory (#366)

* rewrite of the Abstract Factory pattern

* update composer deps

* fixed argument to json_encode which cannot be null

Creational/AbstractFactory/JsonWriter.php

@@ -0,0 +1,8 @@
+<?php
+
+namespace DesignPatterns\Creational\AbstractFactory;
+
+interface JsonWriter
+{
+    public function write(array $data, bool $formatted): string;
+}