Custom PHPStan Rules to Improve Every Symfony project

Using PHPStan is not just about getting to level 8 with less than 100 ignored cases. Yes, there are also [official extensions](https://packagist.org/?query=phpstan%2Fphpstan-) that improve the type support of Symfony, Doctrine, and Laravel projects. But more rules are needed to get our PHP project into a future-proof state. **It takes less effort than getting to level 5 and we can use them since…