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/worker.php

@@ -0,0 +1,14 @@
+<?php
+
+$i = 0;
+do {
+    $ok = frankenphp_handle_request(function () use ($i): void {
+        echo sprintf("Requests handled: %d (request time: %s)\n", $i, $_SERVER['REQUEST_TIME_FLOAT']);
+    
+        var_export($_GET);
+        var_export($_POST);
+        var_export($_SERVER);    
+    });
+
+    $i++;
+} while ($ok);