When user recreate whole cluster certs, multus thick plugin's
previous cert is no longer valid. In such case, we need to prevent
to use cert manager's old certs and restart it from bootstrap
kubeconfig. This fix reloads client config from bootstrap
kubeconfig if cert mgr's cert is failed to load pod.
This change introduces certDuration as parameter to customize
cert duration. In addition, environment variable for node name
is matched to other usages.
This change introduces per-node certification for multus pods.
Once multus pod is launched, then specified bootstrap kubeconfig
is used for initial access, then multus sends CSR request to
kube API to get original certs for kube API access. Once it is
accepted then the multus pod uses generated certs for kube access.
