Support for Leader Ingress labels

[bsosnowski]

Currently, the Ingress resource does not have any labels set. This pull request addresses this issue by incorporating the 'logstream-leader.labels' definition into the Ingress resource.

Additionally, support for Ingress-specific labels has been added, providing flexibility when using features such as Ingress sharding, which requires labels to be set on Ingress objects.

After this change, we can set labels on the Ingress object directly from the values file:

ingress:
  enable: true
  annotations: {}
  labels:
    router-shard: cribl-dedicated-router

The resulting Ingress will have both common and Ingress-specific labels:

apiVersion: networking.k8s.io/v1
kind: Ingress
metadata:
  name: cribl-leader
  labels:
    helm.sh/chart: logstream-leader-4.15.1
    app.kubernetes.io/name: leader
    app.kubernetes.io/instance: cribl
    app.kubernetes.io/version: "4.15.1"
    app.kubernetes.io/managed-by: Helm
    router-shard: cribl-nonprod