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/ChillMainBundle/Tests/Workflow/EntityWorkflowMarkingStoreTest.php

@@ -0,0 +1,61 @@
+<?php
+
+declare(strict_types=1);
+
+/*
+ * Chill is a software for social workers
+ *
+ * For the full copyright and license information, please view
+ * the LICENSE file that was distributed with this source code.
+ */
+
+namespace Chill\MainBundle\Tests\Workflow;
+
+use Chill\MainBundle\Entity\User;
+use Chill\MainBundle\Entity\Workflow\EntityWorkflow;
+use Chill\MainBundle\Workflow\EntityWorkflowMarkingStore;
+use Chill\MainBundle\Workflow\WorkflowTransitionContextDTO;
+use PHPUnit\Framework\TestCase;
+use Symfony\Component\Workflow\Marking;
+
+/**
+ * @internal
+ *
+ * @coversNothing
+ */
+class EntityWorkflowMarkingStoreTest extends TestCase
+{
+    public function testGetMarking(): void
+    {
+        $markingStore = $this->buildMarkingStore();
+        $workflow = new EntityWorkflow();
+
+        $marking = $markingStore->getMarking($workflow);
+
+        self::assertEquals(['initial' => 1], $marking->getPlaces());
+    }
+
+    public function testSetMarking(): void
+    {
+        $markingStore = $this->buildMarkingStore();
+        $workflow = new EntityWorkflow();
+
+        $dto = new WorkflowTransitionContextDTO($workflow);
+        $dto->futureCcUsers[] = $user1 = new User();
+        $dto->futureDestUsers[] = $user2 = new User();
+        $dto->futureDestEmails[] = $email = 'test@example.com';
+
+        $markingStore->setMarking($workflow, new Marking(['foo' => 1]), ['context' => $dto]);
+
+        $currentStep = $workflow->getCurrentStep();
+        self::assertEquals('foo', $currentStep->getCurrentStep());
+        self::assertContains($email, $currentStep->getDestEmail());
+        self::assertContains($user1, $currentStep->getCcUser());
+        self::assertContains($user2, $currentStep->getDestUser());
+    }
+
+    private function buildMarkingStore(): EntityWorkflowMarkingStore
+    {
+        return new EntityWorkflowMarkingStore();
+    }
+}