Istio ingressgateway extraLabels value being stripped out

When adding istio.ingressGateways.igw-name-ingressgateway.extraLabels this doesn't get propagated correctly down to the package. However, they can be set via package overlays eg: istio.values.ingressGateways.igw-name-ingressgateway.extraLabels

Believe we need to shuffle around the templating for building the istio HelmRelease's values so that extraLabels passes through to the package like kubernetesResourceSpec.