Test playbook using molecule (#67)

* Test cluster using molecule

* Fix detection of first control node

* Include --flannel-iface and --node-ip as k3s arguments

* Store logs of k3s-init.service as GitHub job artifacts

collections/requirements.yml

@@ -2,3 +2,4 @@
 collections:
   - name: community.general
   - name: ansible.posix
+  - name: kubernetes.core