Deduplicate kubeadm_patches tasks

kubernetes/control-plane and kubernetes/kubeadm roles both push kubeadm
patches in the same way.
Extract that code and make it a dependency of both.
This is safe because it's only configuration for kubeadm, which only
takes effect when kubeadm is run.

roles/kubernetes/kubeadm_common/tasks/main.yml

@@ -0,0 +1,15 @@
+---
+- name: Kubeadm | Create directory to store kubeadm patches
+  file:
+    path: "{{ kubeadm_patches.dest_dir }}"
+    state: directory
+    mode: "0640"
+  when: kubeadm_patches is defined and kubeadm_patches.enabled
+
+- name: Kubeadm | Copy kubeadm patches from inventory files
+  copy:
+    src: "{{ kubeadm_patches.source_dir }}/"
+    dest: "{{ kubeadm_patches.dest_dir }}"
+    owner: "root"
+    mode: "0644"
+  when: kubeadm_patches is defined and kubeadm_patches.enabled