download submissions route updated which uses function using threads

src/backend/app/submission/submission_routes.py

@@ -19,6 +19,7 @@
 from fastapi import APIRouter, Depends
 from fastapi.logger import logger as logger
 from sqlalchemy.orm import Session
+from fastapi.responses import FileResponse
 
 from ..db import database
 from . import submission_crud
@@ -97,6 +98,10 @@ async def download_submission(
     task_id: The ID of the task. This parameter is optional. If task_id is provided, this endpoint returns the submissions made for this task.
 
     """
+    if not (task_id and export_json):
+        file = submission_crud.download_submission_for_project(db, project_id)
+        return FileResponse(file)
+
     return submission_crud.download_submission(db, project_id, task_id, export_json)