attributesToSearchOn does not support the Objects data type

[macraig]

Cross-posting from meilisearch/meilisearch#5496

---

attributesToSearchOn does not support the Objects data type.

To Reproduce
doc:

{
  "id": 1,
  "ext": {
      "field1": "a",
      "field2": "b"
   }
}

search:

{
  "q": "a",
  "attributesToSearchOn": ["ext"]
}

Expected behavior
search ext.field1 and ext.field2 "ext" == "ext.*"
find doc id:1

please support the ext.* wildcard expression.