Add support of annotations for kuberntes Service

[antonioua]

We have a case when we need to expose Service through Azure Load Balancer.
Currently we are using kustomize and helm post-render to achieve this but it'll be nice to have this configurable in values.yaml.

Proposal config entry in values.yaml:

service:
  annotations:
    service.beta.kubernetes.io/azure-load-balancer-internal: "true"

Resulting Service manifest:

apiVersion: v1
kind: Service
metadata:
  annotations:
    service.beta.kubernetes.io/azure-load-balancer-internal: "true"
  name: prometheus-msteams