feature #32081 [WIP][Mailer] Overwrite envelope sender and recipients from config (Devristo)

This PR was squashed before being merged into the 4.4 branch (closes #32081).

Discussion
----------

[WIP][Mailer] Overwrite envelope sender and recipients from config

| Q             | A
| ------------- | ---
| Branch?       | 4.4
| Bug fix?      | no
| New feature?  | yes
| BC breaks?    | no
| Deprecations? | no
| Tests pass?   | yes    <!-- please add some, will be required by reviewers -->
| Fixed tickets | #31592 #31733   <!-- #-prefixed issue number(s), if any -->
| License       | MIT
| Doc PR        | symfony/symfony-docs#... <!-- required for new features -->

# Description

This MR adds the following configuration, example:

```yaml
# config/packages/mailer.yaml
framework:
  mailer:
    envelope:
      sender: 'sender@example.org'
      recipients: ['redirected@example.org']
```
In turn the `\Symfony\Component\Mailer\EventListener\EnvelopeListener` will be configured to alter the sender and recipient addresses before the message has been sent.

Note: it will only alter the envelope, thus rerouting the message to the correct mailbox. However the message itself will still have the original 'from' and 'to' headers.

# Todos

- [x] Alter configuration and dependency injection
- [x] Create test case
- [ ] Update XML config schema?
- [ ] Doc PR

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 - Bug fixes must be submitted against the lowest maintained branch where they apply
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 - Features and deprecations must be submitted against branch 4.4.
 - Legacy code removals go to the master branch.
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Commits
-------

8e0c8006d8 [WIP][Mailer] Overwrite envelope sender and recipients from config

src/Symfony/Bundle/FrameworkBundle/DependencyInjection/Configuration.php

@@ -1510,6 +1510,22 @@ class Configuration implements ConfigurationInterface
                     ->{!class_exists(FullStack::class) && class_exists(Mailer::class) ? 'canBeDisabled' : 'canBeEnabled'}()
                     ->children()
                         ->scalarNode('dsn')->defaultValue('smtp://null')->end()
+                        ->arrayNode('envelope')
+                            ->info('Mailer Envelope configuration')
+                            ->children()
+                                ->scalarNode('sender')->end()
+                                ->arrayNode('recipients')
+                                    ->performNoDeepMerging()
+                                    ->beforeNormalization()
+                                    ->ifArray()
+                                        ->then(function ($v) {
+                                            return array_filter(array_values($v));
+                                        })
+                                    ->end()
+                                    ->prototype('scalar')->end()
+                                ->end()
+                            ->end()
+                        ->end()
                     ->end()
                 ->end()
             ->end()

src/Symfony/Bundle/FrameworkBundle/DependencyInjection/FrameworkExtension.php

@@ -1922,6 +1922,13 @@ class FrameworkExtension extends Extension
 
         $loader->load('mailer.xml');
         $container->getDefinition('mailer.default_transport')->setArgument(0, $config['dsn']);
+
+        $recipients = $config['envelope']['recipients'] ?? null;
+        $sender = $config['envelope']['sender'] ?? null;
+
+        $envelopeListener = $container->getDefinition('mailer.envelope_listener');
+        $envelopeListener->setArgument(0, $sender);
+        $envelopeListener->setArgument(1, $recipients);
     }
 
     /**

src/Symfony/Bundle/FrameworkBundle/Resources/config/mailer.xml

@@ -25,5 +25,11 @@
             <argument type="service" id="mailer.default_transport" />
             <tag name="messenger.message_handler" />
         </service>
+
+        <service id="mailer.envelope_listener" class="Symfony\Component\Mailer\EventListener\EnvelopeListener">
+            <argument /> <!-- sender -->
+            <argument /> <!-- recipients -->
+            <tag name="kernel.event_subscriber"/>
+        </service>
     </services>
 </container>

src/Symfony/Bundle/FrameworkBundle/Tests/Functional/MailerTest.php

@@ -0,0 +1,62 @@
+<?php
+
+namespace Symfony\Bundle\FrameworkBundle\Tests\Functional;
+
+use Psr\Log\LoggerInterface;
+use Symfony\Component\EventDispatcher\EventDispatcherInterface;
+use Symfony\Component\Mailer\Mailer;
+use Symfony\Component\Mailer\SentMessage;
+use Symfony\Component\Mailer\Transport\AbstractTransport;
+use Symfony\Component\Mime\Address;
+use Symfony\Component\Mime\Email;
+
+class MailerTest extends WebTestCase
+{
+    public function testEnvelopeListener()
+    {
+        self::bootKernel(['test_case' => 'Mailer']);
+
+        $onDoSend = function (SentMessage $message) {
+            $envelope = $message->getEnvelope();
+
+            $this->assertEquals(
+                [new Address('redirected@example.org')],
+                $envelope->getRecipients()
+            );
+
+            $this->assertEquals('sender@example.org', $envelope->getSender()->getAddress());
+        };
+
+        $eventDispatcher = self::$container->get(EventDispatcherInterface::class);
+        $logger = self::$container->get('logger');
+
+        $testTransport = new class($eventDispatcher, $logger, $onDoSend) extends AbstractTransport {
+            /**
+             * @var callable
+             */
+            private $onDoSend;
+
+            public function __construct(EventDispatcherInterface $eventDispatcher, LoggerInterface $logger, callable $onDoSend)
+            {
+                parent::__construct($eventDispatcher, $logger);
+                $this->onDoSend = $onDoSend;
+            }
+
+            protected function doSend(SentMessage $message): void
+            {
+                $onDoSend = $this->onDoSend;
+                $onDoSend($message);
+            }
+        };
+
+        $mailer = new Mailer($testTransport, null);
+
+        $message = (new Email())
+            ->subject('Test subject')
+            ->text('Hello world')
+            ->from('from@example.org')
+            ->to('to@example.org');
+
+        $mailer->send($message);
+    }
+}

src/Symfony/Bundle/FrameworkBundle/Tests/Functional/app/Mailer/bundles.php

@@ -0,0 +1,18 @@
+<?php
+
+/*
+ * This file is part of the Symfony package.
+ *
+ * (c) Fabien Potencier <fabien@symfony.com>
+ *
+ * For the full copyright and license information, please view the LICENSE
+ * file that was distributed with this source code.
+ */
+
+use Symfony\Bundle\FrameworkBundle\FrameworkBundle;
+use Symfony\Bundle\FrameworkBundle\Tests\Functional\Bundle\TestBundle\TestBundle;
+
+return [
+    new FrameworkBundle(),
+    new TestBundle(),
+];

src/Symfony/Bundle/FrameworkBundle/Tests/Functional/app/Mailer/config.yml

@@ -0,0 +1,9 @@
+imports:
+    - { resource: ../config/default.yml }
+
+framework:
+    mailer:
+        envelope:
+            sender: sender@example.org
+            recipients:
+                - redirected@example.org