Create Pod Identity for EKS services

The "GitLab Knowledge Graph" (GKG) team needs to authenticate from EKS to Neptune, an AWS service.

We need to create an AWS Service Account with workload identity mapping for each service hosted on EKS, similar to what we've done on GKE (gitlab-com/gl-infra/platform/runway/provisioner!1102).

Contact from GKG: @michaelangeloio