Kube2iam helm support for custom securityContext

[razorsk8jz]

kube2iam currently does not allow adjustments to securityContext which is required in kubernetes 1.25+ to conform to pod security standards since pod security policies have been deprecated. Update and allow securityContext to be modified via values.yaml or adjust to restrict kube2iam as much as possible

https://kubernetes.io/docs/concepts/security/pod-security-standards/