OS-3825: add cvmfs container configuration

add systemd setup to configure cvmfs via docker-volume-cvmfs.

add new labels to configure cvmfs:

• cvmfs_enabled: if cvmfs configuration should be done (default true)
• cvmfs_tag: which docker-volume-cvmfs tag to use (default latest)

Closes #3825

magnum/drivers/common/templates/fragments/configure-cvmfs.sh

+#!/bin/sh
+
+. /etc/sysconfig/heat-params
+
+if [ "$CVMFS_ENABLED" = "False" ]; then
+    exit 0
+fi
+
+chattr -i /
+mkdir /cvmfs
+chattr +i /
+
+atomic install gitlab-registry.cern.ch/cloud-infrastructure/docker-volume-cvmfs:${CVMFS_TAG}
+
+# add selinux policy
+docker cp docker-volume-cvmfs:/dockercvmfs.pp /tmp
+semodule -i /tmp/dockercvmfs.pp
+
+# install kubernetes volume plugin
+mkdir -p /var/lib/kubelet/plugins/volume/exec/cern~cvmfs
+docker cp docker-volume-cvmfs:/usr/sbin/docker-volume-cvmfs /var/lib/kubelet/plugins/volume/exec/cern~cvmfs/cvmfs
+
+# TODO: move this elsewhere
+lvextend /dev/atomicos/root --size 5G
+xfs_growfs /dev/mapper/atomicos-root