Add private cluster support for namespace creation/validation

[bosesuneha]

Description

Please include the related issue if relevant, and motivation/context. Please also list any dependencies required for this change.

Fixes # (issue)
Feature # (details)

Type of change

• Bug fix (non-breaking change which fixes an issue)
• New feature (non-breaking change which adds functionality)
• Breaking change (fix or feature that would cause existing functionality to not work as expected)
• This change requires a documentation update
• Refactor

How Has This Been Tested?

Provide instructions so we can reproduce, and list any relevant details for your test configuration. Please mention if this is a breaking change which will impact consuming tool(s).

• Unit Test:
• E2E Test:
• Other Test:

Checklist:

• My code follows the style guidelines of this project
• I have performed a self-review of my code
• I have commented my code, particularly in hard-to-understand areas
• I have made corresponding changes to the documentation
• My changes generate no new warnings
• I have added tests that prove my fix is effective or that my feature works
• New and existing unit tests pass locally with my changes
• Any dependent changes have been merged and published in downstream modules

[Vidya2606]

lgtm!