Add Buildbot worker setup to Ansible playbook

Currently assumes the host uses systemd

contrib/ci-workers/templates/buildbot-worker.service.j2

@@ -0,0 +1,17 @@
+[Unit]
+Description=Buildbot worker
+Wants=network.target
+After=network.target
+
+[Service]
+Type=forking
+PIDFile=/home/{{ buildbot_worker_user }}/{{ buildbot_worker_name }}/twistd.pid
+WorkingDirectory=/home/{{ buildbot_worker_user }}
+ExecStart=/usr/local/bin/buildbot-worker start {{ buildbot_worker_name }}
+ExecReload=/usr/local/bin/buildbot-worker restart {{ buildbot_worker_name }}
+ExecStop=/usr/local/bin/buildbot-worker stop {{ buildbot_worker_name }}
+Restart=always
+User={{ buildbot_worker_user }}
+
+[Install]
+WantedBy=multi-user.target

contrib/ci-workers/templates/host.j2

@@ -0,0 +1,4 @@
+OS: {{ ansible_distribution }} {{ ansible_distribution_version }}
+Memory: {{ ansible_memtotal_mb }} MB
+CPU: {{ ansible_processor[1] }}
+{{ buildbot_worker_version.stdout }}