bug #13709 Fix fatal error when OPCache preloading is used (mmenozzi)
bug #13709 Fix fatal error when OPCache preloading is used (mmenozzi)

This PR was merged into the 1.12-dev branch.

Discussion
----------

| Q               | A
| --------------- | -----
| Branch?         | 1.11
| Bug fix?        | yes
| New feature?    | no
| BC breaks?      | no
| Deprecations?   | no
| Related tickets | none
| License         | MIT

While in Symfony 5 the `Symfony\Bundle\FrameworkBundle\Templating\EngineInterface` was removed, in Sylius there were still references to that interface in docblock comments.

With Sylius 1.11 ([with this commit](https://github.com/Sylius/Sylius/commit/ced91b9bd6c3f3d944e57bb54a71fc309c0cb7b0)) the type hint has been promoted to a PHP type hint. This normally does not cause any problem because apparently the class loading is lazy and does not try to load the non-existent interface.

But if PHP OPCache preload is used, like suggested [here](https://symfony.com/doc/current/performance.html#use-the-opcache-class-preloading), it appears that PHP switches to eager class loading and you get the following fatal error:

```
NOTICE: PHP message: PHP Fatal error:  Failed to load class Symfony\Bundle\FrameworkBundle\Templating\EngineInterface used by typed property Sylius\Bundle\ShopBundle\Controller\SecurityWidgetController::$templatingEngine during preloading in Unknown on line 0
```

With this PR we propose to remove all references to the old interface as Symfony 4 is not supported anymore by Sylius.

Commits
-------

1b555f948de7a726f0f3652d479a2ae8319eca92 Remove references to old Symfony FrameworkBundle EngineInterface

Sylius/SyliusUiBundle,Sylius/SyliusUiBundle