add environment variables support (#255)

src/ZM/Config/EnvironmentInterface.php

@@ -0,0 +1,23 @@
+<?php
+
+declare(strict_types=1);
+
+namespace ZM\Config;
+
+interface EnvironmentInterface
+{
+    /**
+     * 设置环境变量
+     */
+    public function set(string $name, mixed $value): self;
+
+    /**
+     * 获取环境变量
+     */
+    public function get(string $name, mixed $default = null): mixed;
+
+    /**
+     * 获取所有环境变量
+     */
+    public function getAll(): array;
+}