feat: add a woker mode (#1)

* refactor: better memory management

* wip

* tmp

* introduce a go-like api

* upgraded to PHP 8.2

* Fix thread safety issues

* fix tests

* wip

* refactor worker

* worker prototype

* fix populate env

* session

* improve tests

* fix Caddy tests

* refactor

testdata/session.php

@@ -0,0 +1,15 @@
+<?php
+
+require_once __DIR__.'/_executor.php';
+
+return function () {
+    session_start();
+
+    if (isset($_SESSION['count'])) {
+        $_SESSION['count']++;
+    } else {
+        $_SESSION['count'] = 0;
+    }
+
+    echo 'Count: '.$_SESSION['count'].PHP_EOL;
+};