Merge pull request kubernetes-sigs#1561 from vincepri/update-deps-1212

🌱 Update dependencies to Kubernetes v1.21.2

Merge pull request kubernetes-sigs#1552 from DirectXMan12/docs/flags-…

…deprecation

📖 Mark all templated flag pieces as deprecated

Merge pull request kubernetes-sigs#1542 from DirectXMan12/infra/add-m…

…issing-license-headers

🌱 Add missing license headers to files

Merge pull request kubernetes-sigs#1532 from vincepri/modify-crd-regi…

…stered

🐛 Envtest should enable conversion only for convertible GVKs

Merge pull request kubernetes-sigs#1531 from vincepri/bug-webhook-con…

…version

🐛 Envtest conversion mods should set strategy and review versions

Merge pull request kubernetes-sigs#1526 from vincepri/handle-crd-webh…

…ook-unstructured

🌱 Handle unstructured CRD objects in envtest webhook mods

Merge pull request kubernetes-sigs#1525 from vincepri/envtest-convers…

…ion-webhook

⚠️ Envtest should modify CRDs appropriately when using webhooks

Merge pull request kubernetes-sigs#1512 from vincepri/bug-webhook-first

🐛 Webhook servers should always start before cache syncs

Merge pull request kubernetes-sigs#1484 from vincepri/wrapmetaonly

🐛 Metadata only objects should always preserve GroupVersionKind

Merge pull request kubernetes-sigs#1451 from vincepri/lock-recorder

🐛 Event recorder should not send events when broadcaster is stopped