cluster-agent: Add network policy default permission

[aureleoules]

What this PR does / why we need it:

This pull requests add the default RBAC permission for listing network policies. This is required for the cluster-agent to collect them.

Checklist

[Place an '[x]' (no spaces) in all applicable fields. Please remove unrelated fields.]

• [x] Chart Version bumped
• [x] Documentation has been updated with helm-docs (run: .github/helm-docs.sh)
• [x] CHANGELOG.md has been updated
• [ ] Variables are documented in the README.md
• [ ] For Datadog Operator chart or value changes update the test baselines (run: make update-test-baselines)

[aureleoules]

Thanks for the review @clamoriniere. I rebased and bumped only the patch digit.

[aureleoules]

Rebased and bumped version