Feature: [docgen] generate documents in an async queue

The documents are now generated in a queue, using symfony messenger. This queue should be configured:

```yaml
# app/config/messenger.yaml
framework:
    messenger:
        # reset services after consuming messages
        # reset_on_message: true

        failure_transport: failed

        transports:
            # https://symfony.com/doc/current/messenger.html#transport-configuration
            async: '%env(MESSENGER_TRANSPORT_DSN)%'
            priority:
                dsn: '%env(MESSENGER_TRANSPORT_DSN)%'
            failed: 'doctrine://default?queue_name=failed'

        routing:
            # ... other messages
            'Chill\DocGeneratorBundle\Service\Messenger\RequestGenerationMessage': priority
```

`StoredObject`s now have additionnal properties:

* status (pending, failure, ready (by default) ), which explain if the document is generated;
* a generationTrialCounter, which is incremented on each generation trial, which prevent each generation more than 5 times;

The generator computation is moved from the `DocGenTemplateController` to a `Generator` (implementing `GeneratorInterface`. 

There are new methods to `Context` which allow to normalize/denormalize context data to/from a messenger's `Message`.

src/Bundle/ChillDocStoreBundle/Resources/public/module/document_action_buttons_group/index.ts

@@ -1,7 +1,8 @@
 import {_createI18n} from "../../../../../ChillMainBundle/Resources/public/vuejs/_js/i18n";
 import DocumentActionButtonsGroup from "../../vuejs/DocumentActionButtonsGroup.vue";
 import {createApp} from "vue";
-import {StoredObject} from "../../types";
+import {StoredObject, StoredObjectStatusChange} from "../../types";
+import {is_object_ready} from "../../vuejs/StoredObjectButton/helpers";
 
 const i18n = _createI18n({});
 
@@ -19,7 +20,7 @@ window.addEventListener('DOMContentLoaded', function (e) {
          };
 
          const
-           storedObject = JSON.parse(datasets.storedObject),
+           storedObject = JSON.parse(datasets.storedObject) as StoredObject,
            filename = datasets.filename,
            canEdit = datasets.canEdit === '1',
            small = datasets.small === '1'
@@ -27,7 +28,20 @@ window.addEventListener('DOMContentLoaded', function (e) {
 
          return { storedObject, filename, canEdit, small };
        },
-       template: '<document-action-buttons-group :can-edit="canEdit" :filename="filename" :stored-object="storedObject" :small="small"></document-action-buttons-group>',
+       template: '<document-action-buttons-group :can-edit="canEdit" :filename="filename" :stored-object="storedObject" :small="small" @on-stored-object-status-change="onStoredObjectStatusChange"></document-action-buttons-group>',
+       methods: {
+         onStoredObjectStatusChange: function(newStatus: StoredObjectStatusChange): void {
+           this.$data.storedObject.status = newStatus.status;
+           this.$data.storedObject.filename = newStatus.filename;
+           this.$data.storedObject.type = newStatus.type;
+
+           // remove eventual div which inform pending status
+           document.querySelectorAll(`[data-docgen-is-pending="${this.$data.storedObject.id}"]`)
+             .forEach(function(el) {
+               el.remove();
+             });
+         }
+       }
      });
 
      app.use(i18n).mount(el);