Support AWS Shield advanced on NLBs not part of ingress controller

[uk-rj]

Currently the ALB controller supports an annotation to enable AWS Shield Advanced for ALB / Ingress resource. alb.ingress.kubernetes.io/shield-advanced-protection

AWS Shield Advanced is also available for NLBs, it would be great if you could provide and annotation and support for enabling of shield-advanced-protection on NLBs created using the service resource. I guess it would also need to provision an elastic IP, linked to the NLB, for advanced shield to work.