1. Add : MsDataset.delete() , support delete dataset file or dir.

2. Add: upload mode,  MsDataset.upload(xx, upload_mode=UploadMode.FORCE_UPLOAD), or  MsDataset.upload(xx, upload_mode=UploadMode.APPEND_UPLOAD)
     if upload_mode = UploadMode.APPEND_UPLOAD, then skip object in case of this object exists.

3. Add: support reload sts token automatically to avoid expire. (current expiration: 24h)

4. Fix: add cookies in api.py for downloading private datasets.
        Link: https://code.alibaba-inc.com/Ali-MaaS/MaaS-lib/codereview/10524449