feat: use gatewayApi.parentRefs instead of gatewayApi.gatewayRef

[nleconte-csgroup]

Description

Use gatewayApi.parentRefs instead of gatewayApi.gatewayRef. This way we can set the HTTPRoute's parent to be either a gateway or a listenerSet.

Before this values :

gatewayApi:
  enabled: true
  gatewayRef:
    name: gateway
    namespace: gateway-system
    sectionName: my-gateway-https-listener-name

Would produce this part in the HTTPRoute :

spec:
  parentRefs:
  - name: gateway
    namespace: gateway-system
    sectionName: my-gateway-https-listener-name

After this PR, we can define the parentRefs with gatewayApi.gatewayRef in the values.yaml file :

gatewayApi:
  enabled: true
  parentRefs:
  - group: gateway.networking.k8s.io
    kind: Gateway
    name: gateway
    namespace: gateway-system
    sectionName: my-gateway-https-listener-name

The part in the HTTPRoute :

spec:
  parentRefs:
  - group: gateway.networking.k8s.io
    kind: Gateway
    name: gateway
    namespace: gateway-system
    sectionName: my-gateway-https-listener-name

But we can now also declare a listenerSet (https://gateway-api.sigs.k8s.io/reference/api-types/listenerset/) instead of a gateway directly. The values.yaml file :

gatewayApi:
  enabled: true
  parentRefs:
  - group: gateway.networking.k8s.io
    kind: ListenerSet
    name: oauth2-proxy
    namespace: gateway-system

The part in the HTTPRoute :

spec:
  parentRefs:
  - group: gateway.networking.k8s.io
    kind: ListenerSet
    name: oauth2-proxy
    namespace: gateway-system

Of course, a listenerSet must be created on the user's side.

Checklist:

• I have bumped the version in the Chart.yaml according to Semantic Versioning.
• I have updated the documentation/CHANGELOG at the bottom of the Chart.yaml
• I have signed off all my commits.
• (Optional) I have updated the Chart.lock for dependency updates
• (Optional) I have implemented helm tests for new feature flags