feature: add spec to specify EventListener service port 🚪

[waveywaves]

Feature request

Update EventListener port to something other than port 8080. The EventListener Service has port config similar to the following. This feature request entails allowing the user to change the "port" to something other than 8080 via a spec change.

ports:
    - protocol: TCP
      port: 8080 <----- this
      targetPort: ??

Currently, ServiceType is something the user can provide to change the type of the service from the default "ClusterIP" to the alternatives (LoadBalancer, NodePort). Similarly, we should also be able to change the port. It can be named ServicePort initially without involving any breaking changes.

Use case

User wants to expose their Webhooks to a port apart from 8080, cuz they need spice 🌶️ in lyf.

[waveywaves]

/assign waveywaves

[dibyom]

cuz they need spice 🌶️ in lyf.

🤣