CLI-54049: add GatewayAPI spec related objects

[luisbarrueco]

This change adds a template definition for stock HTTPRoute and Envoy's HTTPRouteFilter objects that are "compatible" with the definitions we currently have for services ingress:.

This means that we can set

global:
  gatewayAPI:
    enabled: true

and have an application render the HTTPRoute* resources along with the Ingress objects that will allow us to switch the routing from an Ingress controller into an Envoy Gateway GatewayAPI implementation.

The code is a little bit convoluted and totally "coupled" with the way we configure Ingresses today, so it's not a generic/flexible implementation of HTTPRoutes. It has been done like this so that we can migrate traffic away from the ingress-nginx controller without application reconfiguration (other than that global setting.)

[CLAassistant]

All committers have signed the CLA.

[luisbarrueco]

A note to self, so I don't forget later. Maybe it would be best to have

Suggested change

	{{- if and $.Values.global.gatewayAPI.enabled $.Values.global.ingress.enabled -}}
	{{- if $.Values.global.gatewayAPI.enabled -}}

so that we don't run into issues when we try to remove the nginx software eventually?

We are still going to rely on ingress.objects, so we'll need to keep those keys. But the global.ingress part might go away when we eventually uninstall nginx.