Update CODEOWNERS for cilium/api
Update CODEOWNERS for cilium/api

@cilium/api now is a CODEOWNER of the following packages, which are consumed
outside of Cilium and thus need to be treated as part of the Cilium API:

* `pkg/byteorder`
* `pkg/k8s/apis/cilium.io/v2/`
* `pkg/k8s/client/clientset/versioned/`
* `pkg/k8s/client/informers/`
* `pkg/labels`
* `pkg/monitor/api`

Signed-off by: Ian Vernon <ian@cilium.io>

cilium/cilium,tklauser/cilium,tklauser/cilium,tgraf/cilium,cilium-team/cilium,cilium-team/cilium,michi-covalent/cilium,michi-covalent/cilium,michi-covalent/cilium,michi-covalent/cilium,michi-covalent/cilium,tklauser/cilium,cilium/cilium,tgraf/cilium,tklauser/cilium,cilium/cilium,tgraf/cilium,tklauser/cilium,cilium/cilium,cilium/cilium,tgraf/cilium,tgraf/cilium,tgraf/cilium