host-setup: Import datavol Playbook

The `host-setup.yml` playbook now imports the `datavol.yml` playbook, so
that new machines (particularly those provisioned by the
host-provisioner) get their data volumes formatted and mounted
automatically.

datavol.yml

@@ -13,6 +13,7 @@
       name: >-
         {{
           data_volumes
+          | d([])
           | map(attribute='fstype')
           | map('extract', mkfs_package)
           | list

host-setup.yml

@@ -4,3 +4,4 @@
 - import_playbook: collectd.yml
 - import_playbook: promtail.yml
 - import_playbook: auto-updates.yml
+- import_playbook: datavol.yml