[process-agent] add k8s namespace cluster corecheck

[fisherevans]

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What does this PR do?

Collects details on the k8s namespaces defined within the cluster

Motivation

This is a often referenced resource type in K8S - but is missing from our current product dataset.

Additional Notes

The namespace resource is very minimal - these changes were primarily a replication of a similarly bare-bones resource: role bindings.

It depends on https://github.com/DataDog/agent-payload/pull/177

Possible Drawbacks / Trade-offs

Describe how to test/QA your changes

To be tested on all supported versions of k8s

Reviewer's Checklist

• [ ] If known, an appropriate milestone has been selected; otherwise the Triage milestone is set.
• [ ] Use the major_change label if your change either has a major impact on the code base, is impacting multiple teams or is changing important well-established internals of the Agent. This label will be use during QA to make sure each team pay extra attention to the changed behavior. For any customer facing change use a releasenote.
• [ ] A release note has been added or the changelog/no-changelog label has been applied.
• [ ] Changed code has automated tests for its functionality.
• [ ] Adequate QA/testing plan information is provided if the qa/skip-qa label is not applied.
• [ ] At least one team/.. label has been applied, indicating the team(s) that should QA this change.
• [ ] If applicable, docs team has been notified or an issue has been opened on the documentation repo.
• [ ] If applicable, the need-change/operator and need-change/helm labels have been applied.
• [ ] If applicable, the k8s/<min-version> label, indicating the lowest Kubernetes version compatible with this feature.
• [ ] If applicable, the config template has been updated.

[bits-bot]

All committers have signed the CLA.