Support for sub-folders when mounting S3 buckets

[srikumar003]

Enables datasets to be defined on subfolders in S3 buckets. A dataset such as:

apiVersion: com.ie.ibm.hpsys/v1alpha1
kind: Dataset
metadata:
name: test
spec:
   local:
   type: "COS"
   secret-name: "secret-name"
   endpoint: "http://s3.eu.cloud-object-storage.appdomain.cloud"
   bucket: "bucket/folder"

should have only the contents of bucket/folder available under /mnt/datasets/test when mounted into a pod.

However, if the dataset is used as a configmap this will not prevent the pod from accessing the contents of the bucket.

[vytautaskelmelissislt]

It is like https://github.com/kubernetes-sigs/nfs-subdir-external-provisioner

[Trainbow]

已收到，谢谢！

[Trainbow]

已收到，谢谢！