Set container level securityContext for Affinity assistant

[kristofferchr]

Feature request

Set container level securityContext for affinity assistant. Reuses feature flag set-security-context. This feature needs to take into account if the os is windows

Use case

This change is needed for the Affinity assistant to adhere to restriced pod security standards. This change is a prerequisite for implementing readOnlyRootFilesystem for all containers.

[kristofferchr]

/assign