pikvm: Add role/playbook for PiKVM

PiKVM comes with its own custom Arch Linux-based operating systems.  We
want to be able to manage it with our configuration policy, especially
for setting up authentication, etc.  It won't really work with the
host-provisioner without some pretty significant changes to the base
playbooks, but we can control some bits directly.

roles/pikvm/files/sshd_config

@@ -0,0 +1,2 @@
+PermitRootLogin prohibit-password
+PasswordAuthentication no