Support GatewayAPI's ListenerSet (GEP-1713)

[hjoshi123]

Is there an existing issue for this?

• I have searched the existing issues

Does this enhancement require public documentation?

• I have added an Acceptance Criteria item for adding and/or adjusting public documentation (if applicable)

Problem Statement

GatewayAPI has proposed XListenerSet (which will eventually be called ListenerSet) to address issues associated with gateway being the single resource where listeners can be attached. This resource also increases the limit of listeners that can be attached to a single gateway.
More on this here. Since KIC does support GatewayAPI, it would be optimal to support this resource too so that the role of listeners could be shifted to application developers instead of cluster operators.

Proposed Solution

• Implement support for XListenerSet according to the GEP proposal.

Additional information

This might need to be a feature gate initially for users to test while the transition from XListenerSet to ListenerSet happens.

Acceptance Criteria

• [] As a user I can create XListenerSet resource belonging to a parent gateway and kong has the ability route traffic.
• [] As a user I should be able to configure allowedListeners for a gateway.