Return tempFiles

Add the response data to the return. Fixes umbraco#11278

src/Umbraco.Web.BackOffice/Controllers/MediaController.cs

@@ -858,7 +858,7 @@ public async Task<IActionResult> PostAddFile([FromForm] string path, [FromForm]
                 }
             }
 
-            return Ok();
+            return Ok(tempFiles);
         }
 
         private IMedia FindInChildren(int mediaId, string nameToFind, string contentTypeAlias)