Enable usage of different service accounts for Kube-Bench, Kube-Hunter, Trivy, ...

[christianhuth]

Problem:
At the moment every pod started by the starboard operator will use the service account associated with the starboard-operator pod. This is bad in cases where you want the starboard operator to run e.g. without root privileges. Then e.g. kube-bench is not able to start.

Solution:
Start kube-bench, kube-hunter and trivy-scanner pods with their own serviceaccount, so we can give these pods their needed privileges via psp and rbac.