cli: Add argument for namespace

[jochenseeber]

Allows accessing Kadalu installations installed in other namespaces than the default "kadalu"

What this PR does / why we need it:

This is useful for multi-tenant setups where multiple Kadalu instances run in different namespaces.

Which issue(s) this PR fixes:

No issue

Special notes for your reviewer:

Checklist

• Documentation added
• Tests updated
• Add an entry in the CHANGELOG.md about the changes.

[leelavg]

where multiple Kadalu instances

• Could you pls specify the intention a bit more clearly? You can deploy Kadalu CRs in multiple namespaces and operator running in kadalu ns can reconcile based on that
• The code changes are for running Kadalu Operator & CSI in a different ns and multiple collides with that intention as CSI pods should be running in single namespace only.

btw, pls do sign your commit (git commit --amend -s --no-edit), thanks.