Switch to Kubernetes secret instead of users credentials

[harshad16]

Switch to Kubernetes secret instead of users credentials
Closes: #1415

Description

• switch the cos_auth_type: KUBERNETES_SECRET
  https://elyra.readthedocs.io/en/latest/user_guide/runtime-conf.html#cloud-object-storage-authentication-type-cos-auth-type
• include cos_secret which reference the secret in the cluster with details of auth

How Has This Been Tested?

Test Impact

Request review criteria:

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• The developer has manually tested the changes and verified that the changes work
• The developer has added tests or explained why testing cannot be added (unit tests & storybook for related changes)

[andrewballantyne]

/hold

Let us test the image first before merging.

[openshift-ci]

[APPROVALNOTIFIER] This PR is APPROVED

This pull-request has been approved by: andrewballantyne

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[harshad16]

Tested on a cluster:

The changes are showing up nicely in the generation.

[andrewballantyne]

/unhold

LGTM