`linkerd authz` (and some `linkerd viz` paths) only recognize `HTTPRoute.policy.linkerd.io`

Summary

The CLI only understands policy.linkerd.io. linkerd authz calls k8s.AuthorizationsForResource (cli/cmd/authz.go:62), which in pkg/k8s/policy.go:138 does:

} else if target.Kind == HTTPRouteKind && target.Group == PolicyAPIGroup {
        route, err := k8sAPI.L5dCrdClient.PolicyV1alpha1().HTTPRoutes(p.Namespace).Get(ctx, string(target.Name), metav1.GetOptions{})

with PolicyAPIGroup = "policy.linkerd.io" (pkg/k8s/k8s.go:41).

As a consequence, an AuthorizationPolicy targeting HTTPRoute.gateway.networking.k8s.io is silently dropped from the linkerd authz output; users get an empty/partial authorization list for a workload that is in fact authorized.

Expected behaviour

1. linkerd authz resolves AuthorizationPolicy targets in both policy.linkerd.io and gateway.networking.k8s.io.
2. The output disambiguates the group, e.g. a ROUTE column value of HTTPRoute.gateway.networking.k8s.io/my-route (or an extra column), since the same name can exist in both groups.
3. At minimum, unrecognized target kinds/groups produce a warning on stderr instead of being silently skipped, consistent with the other error paths in AuthorizationsForResource.

Notes / dependencies

Implementing (1) with typed clients needs gateway-api Go types; the repo currently pins sigs.k8s.io/gateway-api v0.8.1 (go.mod:53), which predates the v1 API surface. See https://github.com/linkerd/linkerd2/issues/15619

How can it be reproduced?

# with the gateway-api CRDs installed
kubectl apply -f - <<'YAML'
apiVersion: gateway.networking.k8s.io/v1
kind: HTTPRoute
metadata:
  name: gw-route
  namespace: emojivoto
spec:
  parentRefs:
    - group: policy.linkerd.io
      kind: Server
      name: web-http
  rules:
    - matches:
        - path:
            type: PathPrefix
            value: /
---
apiVersion: policy.linkerd.io/v1alpha1
kind: AuthorizationPolicy
metadata:
  name: gw-route-authz
  namespace: emojivoto
spec:
  targetRef:
    group: gateway.networking.k8s.io
    kind: HTTPRoute
    name: gw-route
  requiredAuthenticationRefs:
    - kind: ServiceAccount
      name: default
      namespace: emojivoto
YAML

linkerd authz -n emojivoto deploy/web
# the gw-route-authz row is missing, with no warning