Pass LAMBDA_REQUEST_ID to PHP-FPM

The function and console runtimes set it on every invocation, PHP-FPM workers only received
LAMBDA_INVOCATION_CONTEXT.

Claude-Session: https://claude.ai/code/session_0168N55uBK9UjfpL6r8oGjDm

Author: mnapoli

docs/runtimes/fpm-runtime.mdx

@@ -70,6 +70,8 @@ Here is an example to retrieve it:
 $lambdaContext = json_decode($_SERVER['LAMBDA_INVOCATION_CONTEXT'], true);
 ```
 
+The request ID of the invocation is also available directly in `$_SERVER['LAMBDA_REQUEST_ID']`, like in [the other runtimes](./runtimes-details.mdx#environment-variables).
+
 ### Request context
 
 API Gateway integrations can add information to the HTTP request via the *request context*.

src/FpmRuntime/FpmHandler.php

@@ -253,6 +253,8 @@ private function eventToFastCgiRequest(HttpRequestEvent $event, Context $context
         $request->setCustomVar('PATH_INFO', $event->getPath());
         $request->setCustomVar('QUERY_STRING', $event->getQueryString());
         $request->setCustomVar('LAMBDA_INVOCATION_CONTEXT', json_encode($context, JSON_THROW_ON_ERROR));
+        // Same variable as in the other runtimes, see LambdaRuntime::processNextEvent()
+        $request->setCustomVar('LAMBDA_REQUEST_ID', $context->getAwsRequestId());
         $request->setCustomVar('LAMBDA_REQUEST_CONTEXT', json_encode($event->getRequestContext(), JSON_THROW_ON_ERROR));
 
         $contentType = $event->getContentType();

tests/FpmRuntime/FpmHandlerTest.php

@@ -1325,6 +1325,7 @@ private function assertCommonServerVariables(array $response, array $expectedGlo
             'SCRIPT_FILENAME' => __DIR__ . '/fixtures/request.php',
             'GATEWAY_INTERFACE' => 'FastCGI/1.0',
             'FCGI_ROLE' => 'RESPONDER',
+            'LAMBDA_REQUEST_ID' => 'abc',
         ];
 
         // Allow to override some keys