Add KVM hypervisor playbook to contrib

Optional Ansible playbook for preparing a host for running Kargo.
This includes creation of a user account, some basic packages,
and sysctl values required to allow CNI networking on a libvirt network.

contrib/kvm-setup/kvm-setup.yml

@@ -0,0 +1,8 @@
+---
+- hosts: localhost
+  gather_facts: False
+  become: yes
+  vars:
+    - bootstrap_os: none
+  roles:
+    - kvm-setup