Product images deletion fix

[Zales0123]

Q	A
Branch?	1.2
Bug fix?	yes
New feature?	no
BC breaks?	no
Deprecations?	no
Related tickets
License	MIT

Before

The problem was, whenever product deletion failed (for example because the variant is already used in a placed order), images files were still removed. The reason for that was, that the ImagesRemoveListener were listening on postRemove doctrine event, which is called even if flush ends with an error.

Proposed solution

I've refactored ImagesRemoveListener to listen on both onFlush and postFlush events. It saves paths from scheduled to remove entities with ImageInterface type and removes them with ImageUploader and CacheManager when the whole transaction passes (is there any BC Break? cc @pamil).

Test

During the implementation, I've encountered some problems with images assertions in Behat tests. The problem was, the images files in the cache were not generated while visiting them with mink driver in Behat page. I propose a new service ImageExistenceChecker, which is based on checking the existence of a file, rather than visiting checked file URL (which I find a little bit more appropriate). I'm not sure about the implementation - I suppose I could have made too many assumptions about the folders structure (parameter %__symfony__.kernel.project_dir%/web/ should be for sure changed in Sylius 1.3+) and I would be grateful for any ideas how this service can be improved/simplified.

Nonetheless, it works and fixes a bug, which is definitely a good thing 😄 🐃

[GSadee]

I guess that it fixes #8899 and closes #8909