Handle directories for dataset/version creation. (#255)

Update kagglehub SDK to support dataset upload with sub-dirs.

PRESUBMIT=[kaggleazure
pr](Kaggle/kaggleazure#37081)

BUGS=439905909

**Tested**
Tested locally with
- Dataset creation: [new creation of
dataset](https://screenshot.googleplex.com/A5tQsZTLSX2ZzLc)
- Dataset Version creation: [update dataset to
v2](https://screenshot.googleplex.com/BagrxgyzDsURTQB)

Author: dolaameng

src/kagglehub/datasets_helpers.py

@@ -14,6 +14,7 @@ def _create_dataset(dataset_handle: DatasetHandle, files_and_directories: Upload
         "ownerSlug": dataset_handle.owner,
         "title": dataset_handle.dataset,
         "files": [{"token": file_token} for file_token in files_and_directories.files],
+        "directories": files_and_directories.serialize()["directories"],
         "isPrivate": True,
     }
 
@@ -30,6 +31,7 @@ def _create_dataset_version(
     data = {
         "versionNotes": version_notes,
         "files": [{"token": file_token} for file_token in files_and_directories.files],
+        "directories": files_and_directories.serialize()["directories"],
     }
     api_client = KaggleApiV1Client()
     api_client.post(f"/datasets/create/version/{dataset_handle.owner}/{dataset_handle.dataset}", data)