Add support for PHP 8.4 Lazy Objects RFC with configuration flag

[beberlei]

Our goal is that we can completely replace all kinds of code for proxy generation and proxy usage with the new lazy objects feature of PHP 8.4: https://wiki.php.net/rfc/lazy-objects

In 3.4.x we can add support for optionally using lazy objects, and in 4.x we increase the requirement for PHP to 8.4 and automatically always use lazy objects.

The benefit of lazy objects is that we don't need code-generation anymore, and that it also allows us to treat partial objects as lazy objects that can load their missing properties only when accessed.

See #11659 for prerequisites of using new Reflection APIs.

Use:

$config = new \Doctrine\ORM\Configuration();
$config->enableNativeLazyObjects(true);

To run tests with this ENABLE_NATIVE_LAZY_OBJECTS=1 php vendor/bin/phpunit.

[GromNaN]

Well done!

[nicolas-grekas]

Well done, so happy it works this seamlessly :)
I agree with @GromNaN : the term proxy is now inaccurate; this uses the ghost strategy, no proxy is involved.

[greg0ire]

@jaapio the docs build suddenly fails, what should we do?

[jaapio]

You need to update phpDocumentor/filesystem. As this is an unexpected breaking change. But it's fixed when you update the package.

[greg0ire]

I made doctrine/.github#60 from my phone 📱