support IBM Cloud IAM API Key instead of HMAC keypair when configuring COS bucket as dataset

[shawnzhu]

The use case is about working with data on IBM COS. I followed the guide here: https://github.com/IBM/dataset-lifecycle-framework/wiki/Data-Volumes-for-Notebook-Servers#create-a-dataset-for-the-s3-bucket

where it creates a COS bucket, it needs:

apiVersion: com.ie.ibm.hpsys/v1alpha1
kind: Dataset
metadata:
  name: your-dataset
spec:
  local:
    type: "COS"
    accessKeyID: "access_key_id"
    secretAccessKey: "secret_access_key"
    endpoint: "https://YOUR_ENDPOINT"
    bucket: "YOUR_BUCKET"
    region: "" #it can be empty

Which requires a service credential to be created.

I wonder if it can support creating dataset via:

apiVersion: com.ie.ibm.hpsys/v1alpha1
kind: Dataset
metadata:
  name: your-dataset
spec:
  local:
    type: "COS"
    ibm_cloud_iam_apikey: "<base64 encoded api key>"
    bucket: "YOUR_BUCKET"
    region: "" #it can be empty

Which will make COS admin's life much easier since it can delegate secret management/rotate to IBM Cloud IAM.