Send an email when a workflow is send to an external

- create an event subscriber to catch the workflow which arrive to a "sentExternal" step;
- add a messenger's message to handle the generation of the email;
- add a simple message, and a simple controller for viewing the document
- add dedicated tests

src/Bundle/ChillMainBundle/config/services.yaml

@@ -33,15 +33,15 @@ services:
     # workflow related
     Chill\MainBundle\Workflow\:
         resource: '../Workflow/'
-        autowire: true
-        autoconfigure: true
 
     Chill\MainBundle\Workflow\EntityWorkflowManager:
-        autoconfigure: true
-        autowire: true
         arguments:
             $handlers: !tagged_iterator chill_main.workflow_handler
 
+    # seems to have no alias on symfony 5.4
+    Symfony\Component\Mime\BodyRendererInterface:
+        alias: 'twig.mime_body_renderer'
+
     # other stuffes
 
     chill.main.helper.translatable_string: