Description:
Currently, there's no way to apply custom labels across all resources created by the Envoy Proxy Gateway Helm chart. Users often need to add organisational labels (like owner, team, cost-center, etc.) to all Kubernetes resources for resource management, cost tracking, and governance purposes.

Proposal:
Add a new commonLabels field in the values.yaml of the helm chart. Update the _helpers.tpl and the YAML files accordingly to make use of the commonLabels. Values defined under this will add labels to all the kubernetes resources.