// CreateAPIServerCertAndKeyFiles create a new certificate and key files for the apiserver.
// If the apiserver certificate and key files already exists in the target folder, they are used only if evaluated equal; otherwise an error is returned.
// It assumes the cluster CA certificate and key files should exists into the CertificatesDir
// It assumes the cluster CA certificate and key files exist in the CertificatesDir.
// CreateAPIServerKubeletClientCertAndKeyFiles create a new CA certificate for kubelets calling apiserver
// CreateAPIServerKubeletClientCertAndKeyFiles create a new certificate for kubelets calling apiserver.
// If the apiserver-kubelet-client certificate and key files already exists in the target folder, they are used only if evaluated equals; otherwise an error is returned.
// It assumes the cluster CA certificate and key files should exists into the CertificatesDir
// It assumes the cluster CA certificate and key files exist in the CertificatesDir.
// CreateFrontProxyClientCertAndKeyFiles create a new certificate for proxy server client.
// If the front-proxy-client certificate and key files already exists in the target folder, they are used only if evaluated equals; otherwise an error is returned.
// It assumes the front proxy CAA certificate and key files should exists into the CertificatesDir
// It assumes the front proxy CA certificate and key files exist in the CertificatesDir.