kubernetes: Manage worker nodes

So far, I have been managing Kubernetes worker nodes with Fedora CoreOS
Ignition, but I have decided to move everything back to Fedora and
Ansible.  I like the idea of an immutable operating system, but the FCOS
implementation is not really what I want.  I like the automated updates,
but that can be accomplished with _dnf-automatic_.  I do _not_ like
giving up control of when to upgrade to the next Fedora release.
Mostly, I never did come up with a good way to manage application-level
configuration on FCOS machines.  None of my experiments (Cue+tmpl,
KCL+etcd+Luci) were successful, which mostly resulted in my manually
managing configuration on nodes individually.  Managing OS-level
configuration is also rather cumbersome, since it requires redeploying
the machine entirely.  Altogether, I just don't think FCOS fits with my
model of managing systems.

This commit introduces a new playbook, `kubernetes.yml`, and a handful of
new roles to manage Kubernetes worker nodes running Fedora Linux.  It
also adds two new deploy scripts, `k8s-worker.sh` and `k8s-longhorn.sh`,
which fully automate the process of bringing up worker nodes.

roles/cri-o/tasks/main.yml

@@ -0,0 +1,47 @@
+- name: ensure cri-o is installed
+  package:
+    name:
+    - container-selinux
+    - cri-o
+    - crun
+    state: present
+  tags:
+  - install
+
+- name: ensure crio configuration drop-in directory exists
+  file:
+    path: /etc/crio/crio.conf.d
+    owner: root
+    group: root
+    mode: u=rwx,go=rx
+    state: directory
+  tags:
+  - config
+
+- name: ensure cri-o is configured to use crun
+  copy:
+    src: crun.conf
+    dest: /etc/crio/crio.conf.d/10-crio-crun.conf
+    owner: root
+    group: root
+    mode: u=rw,go=r
+  notify:
+  - restart crio
+  tags:
+  - config
+
+- name: flush handlers
+  meta: flush_handlers
+
+- name: ensure cri-o service is enabled
+  service:
+    name: crio
+    enabled: true
+  tags:
+  - service
+- name: ensure cri-o service is running
+  service:
+    name: crio
+    state: started
+  tags:
+  - service