Move kubernetes/master to kubernetes/control-plane (#7218)

This is a small step to replace "master" with "control-plane" in
Kubespray project.

roles/kubernetes/control-plane/tasks/kubeadm-etcd.yml

@@ -0,0 +1,32 @@
+---
+- name: Calculate etcd cert serial
+  command: "openssl x509 -in {{ kube_cert_dir }}/apiserver-etcd-client.crt -noout -serial"
+  register: "etcd_client_cert_serial_result"
+  changed_when: false
+  tags:
+    - network
+
+- name: Set etcd_client_cert_serial
+  set_fact:
+    etcd_client_cert_serial: "{{ etcd_client_cert_serial_result.stdout.split('=')[1] }}"
+  tags:
+    - network
+
+- name: Ensure etcdctl binary is installed
+  include_tasks: "{{ role_path }}/../../etcd/tasks/install_host.yml"
+  vars:
+    etcd_cluster_setup: true
+  when: etcd_deployment_type == "host" and not etcd_kubeadm_enabled
+
+- name: Ensure etcdctl binary is installed
+  include_tasks: "{{ role_path }}/../../etcd/tasks/install_etcdctl_docker.yml"
+  vars:
+    etcd_cluster_setup: true
+    etcd_retries: 4
+  when:
+    - etcd_deployment_type == "docker" and not etcd_kubeadm_enabled
+
+- name: Ensure etcdctl script is installed
+  import_role:
+    name: etcdctl
+  when: etcd_kubeadm_enabled