Review gatekeepr-libary rules vs upstream

[NissesSenap]

In https://github.com/open-policy-agent/gatekeeper-library/ there is a bunch of good rules that we should be using.

• Disallow PDB lower than deployment replicas: https://github.com/open-policy-agent/gatekeeper-library/tree/master/library/general/poddisruptionbudget
• unique serviceselectors: https://github.com/open-policy-agent/gatekeeper-library/tree/master/library/general/uniqueserviceselector (would this create any issues for us? This sound vey sound in general).
• Disable the option of changing SA on a pod https://github.com/open-policy-agent/gatekeeper-library/tree/master/library/general/noupdateserviceaccount (this might create issues for AKS/EKS but hopefully they shouldn't)
• No rule/clusterrolebinding towards anonymous users: https://github.com/open-policy-agent/gatekeeper-library/tree/master/library/general/disallowanonymous

There are probably more options. So check it out.