Add HA option, change to yaml inventory, cleanup

- HA option for multiple server nodes using embedded etcd
- Switch to yaml inventory file for easier editing and combining vars
- Update to full ansible module names
- Change master/node names to server/agent
- Cleanup small linting errors
- Add reboot playbook which staggers reboot to keep HA cluster up
- Move playbooks to playbook directory

Signed-off-by: Derek Nola <derek.nola@suse.com>

playbook/site.yml

@@ -0,0 +1,21 @@
+---
+- name: Cluster prep
+  hosts: k3s_cluster
+  gather_facts: true
+  become: true
+  roles:
+    - role: prereq
+    - role: download
+    - role: raspberrypi
+
+- name: Setup K3S server
+  hosts: server
+  become: true
+  roles:
+    - role: k3s/server
+
+- name: Setup K3S agent
+  hosts: node
+  become: true
+  roles:
+    - role: k3s/agent