AKS: Ingress controller support (AGIC or NGINX)

[mitchdenny]

Problem

AKS deployments with WithExternalHttpEndpoints() need an ingress controller to expose services externally. Currently, services are exposed via ClusterIP (or LoadBalancer if configured) but there's no built-in ingress controller provisioning.

Options

• Application Gateway Ingress Controller (AGIC) — Azure-native
• NGINX Ingress Controller — community standard
• Traefik — alternative

Expected

var aks = builder.AddAzureKubernetesEnvironment("aks")
    .WithApplicationGatewayIngress();  // or .WithNginxIngress()

Related

Part of AKS hosting support (PR #16088)