✨(back) add endpoint checking media status

With the usage of a malware detection system, we need a way to know the
file status. The front will use it to display a loader while the analyse
is not ended.

src/backend/core/models.py

@@ -835,6 +835,7 @@ class Document(MP_Node, BaseModel):
             "ai_transform": ai_access,
             "ai_translate": ai_access,
             "attachment_upload": can_update,
+            "media_check": can_get,
             "children_list": can_get,
             "children_create": can_update and user.is_authenticated,
             "collaboration_auth": can_get,