allow to set aio_variables from containers.json

Signed-off-by: Simon L <szaimen@e.mail.de>

php/src/Container/AioVariables.php

@@ -0,0 +1,19 @@
+<?php
+
+namespace AIO\Container;
+
+class AioVariables {
+    /** @var string[] */
+    private array $variables = [];
+
+    public function AddVariable(string $variable) : void {
+        $this->variables[] = $variable;
+    }
+
+    /**
+     * @return string[]
+     */
+    public function GetVariables() : array {
+        return $this->variables;
+    }
+}