Refactor workflow classes and forms

- the workflow controller add a context to each transition;
- the state of the entity workflow is applyied using a dedicated marking store
- the method EntityWorkflow::step use the context to associate the new step with the future destination user, cc users and email. This makes the step consistent at every step.
- this allow to remove some logic which was processed in eventSubscribers,
- as counterpart, each workflow must specify a dedicated marking_store:

```yaml
framework:
    workflows:
        vendee_internal:
            # ...
            marking_store:
                service: Chill\MainBundle\Workflow\EntityWorkflowMarkingStore
```

src/Bundle/ChillDocStoreBundle/Workflow/AccompanyingCourseDocumentWorkflowHandler.php

@@ -121,9 +121,4 @@ class AccompanyingCourseDocumentWorkflowHandler implements EntityWorkflowHandler
     {
         return AccompanyingCourseDocument::class === $entityWorkflow->getRelatedEntityClass();
     }
-
-    public function supportsFreeze(EntityWorkflow $entityWorkflow, array $options = []): bool
-    {
-        return false;
-    }
 }