test: kubectl-validate manifests in presubmit

[chewong]

This PR adds manifest validation with kubectl-validate to ensure manifests used in docs are up-to-date.

Fixes #679

Test output:

hack/verify-all.sh -v

/var/folders/90/j8qmvdf56xzd56qcj_rcfmjr0000gn/T/tmp.qsIgrSswW3/crd-all.gen.yaml...OK

/var/folders/90/j8qmvdf56xzd56qcj_rcfmjr0000gn/T/tmp.qsIgrSswW3/gateway.networking.k8s.io_gateways.yaml...OK

/var/folders/90/j8qmvdf56xzd56qcj_rcfmjr0000gn/T/tmp.qsIgrSswW3/gateway.networking.k8s.io_httproutes.yaml...OK

/var/folders/90/j8qmvdf56xzd56qcj_rcfmjr0000gn/T/tmp.qsIgrSswW3/inference.networking.x-k8s.io_inferencemodels.yaml...OK

/var/folders/90/j8qmvdf56xzd56qcj_rcfmjr0000gn/T/tmp.qsIgrSswW3/inference.networking.x-k8s.io_inferencepools.yaml...OK

/var/folders/90/j8qmvdf56xzd56qcj_rcfmjr0000gn/T/tmp.qsIgrSswW3/networking.gke.io_gcpbackendpolicies.yaml...OK

/var/folders/90/j8qmvdf56xzd56qcj_rcfmjr0000gn/T/tmp.qsIgrSswW3/networking.gke.io_healthcheckpolicies.yaml...OK

config/manifests/benchmark/benchmark.yaml...OK

config/manifests/benchmark/model-server-service.yaml...OK

config/manifests/gateway/gke/gateway.yaml...OK

config/manifests/gateway/gke/gcp-backend-policy.yaml...OK

config/manifests/gateway/gke/healthcheck.yaml...OK

config/manifests/gateway/gke/httproute.yaml...OK

config/manifests/gateway/istio/destination-rule.yaml...OK

config/manifests/gateway/istio/gateway.yaml...OK

config/manifests/gateway/istio/httproute.yaml...OK

config/manifests/gateway/kgateway/gateway.yaml...OK

config/manifests/gateway/kgateway/httproute.yaml...OK

config/manifests/inferencemodel.yaml...OK

config/manifests/inferencepool-resources.yaml...OK

config/manifests/regression-testing/inferencemodel.yaml...OK

config/manifests/regression-testing/multi-lora-regression.yaml...OK

config/manifests/regression-testing/single-workload-regression.yaml...OK

config/manifests/regression-testing/vllm/multi-lora-deployment.yaml...OK

config/manifests/vllm/cpu-deployment.yaml...OK

config/manifests/vllm/gpu-deployment.yaml...OK

config/manifests/vllm/sim-deployment.yaml...OK
SUCCESS: hack/../hack/verify-manifests.sh
Verified 209 file headers match boilerplate
SUCCESS: hack/../hack/verify-boilerplate.sh
Skipping hack/../hack/verify-all.sh

[netlify]

✅ Deploy Preview for gateway-api-inference-extension ready!

Name	Link
🔨 Latest commit	13d4101
🔍 Latest deploy log	https://app.netlify.com/projects/gateway-api-inference-extension/deploys/68796e3ff4aa87000860e640
😎 Deploy Preview	https://deploy-preview-1083--gateway-api-inference-extension.netlify.app
📱 Preview on mobile	Toggle QR Code... Use your smartphone camera to open QR code link.

---

To edit notification comments on pull requests, go to your Netlify project configuration.

[nirrozenbaum]

cc @robscott

[kfswain]

Apologies for the delay @chewong. This looks great. Just one small comment. Will pass back with a LGTM when thats updated.

/approve

[k8s-ci-robot]

[APPROVALNOTIFIER] This PR is APPROVED

This pull-request has been approved by: chewong, kfswain

The full list of commands accepted by this bot can be found here.

The pull request process is described here

Needs approval from an approver in each of these files:

• OWNERS [kfswain]

Approvers can indicate their approval by writing /approve in a comment
Approvers can cancel approval by writing /approve cancel in a comment

[kfswain]

/lgtm