Merge #3067

3067: Fix task details serialization r=Kerollmops a=ManyTheFish

# Pull Request

- document addition task details always contain the field `indexedDocuments`
  - value is set to `null` when the task is enqueued or processing
  - value is set to `0` when the task is canceled or failed
- the field `deletedDocuments` of the document deletion task details is set to `0` when the task is canceled or failed
- the field `deletedDocuments` of the document clearAll task details is set to `0` when the task is canceled or failed
- the field `deletedTasks` of the task deletion task details is set to `0` when the task is canceled or failed
- the field `canceledTasks` of the task cancelation task details is set to `0` when the task is canceled or failed

## Related issue
Fixes #3057
Fixes #3058


Co-authored-by: ManyTheFish <many@meilisearch.com>

meilisearch-http/tests/tasks/mod.rs

@@ -412,7 +412,7 @@ async fn test_summarized_delete_batch() {
       "canceledBy": null,
       "details": {
         "matchedDocuments": 3,
-        "deletedDocuments": null
+        "deletedDocuments": 0
       },
       "error": {
         "message": "Index `test` not found.",
@@ -471,7 +471,7 @@ async fn test_summarized_delete_document() {
       "canceledBy": null,
       "details": {
         "matchedDocuments": 1,
-        "deletedDocuments": null
+        "deletedDocuments": 0
       },
       "error": {
         "message": "Index `test` not found.",