Secret Sync for the config repo token, one-time enrollment code, check output (#401)

* cce: Fetch the config repository token via Secret Sync

* Keep the Secret Sync GitLab token across reboots and outages

* Install site configuration with a one-time enrollment code

* Align the itcc and dhki cases in prepare-system.sh

* Report an unreachable broker instead of a clock skew during install

* Show bridgehead check results as OK, WARN or CRIT and run them during install

* Refresh the config repo token before bridgehead check fetches

* Skip Secret Sync until the private key and root certificate exist

* Indent the case block in prepare-system.sh with tabs only

* Hide the config repo URL, token and enrollment code from other local users

* remove the unreachable second dhki case

---------

Co-authored-by: Martin Lablans <m.lablans@dkfz-heidelberg.de>

lib/prerequisites.sh

@@ -72,6 +72,7 @@ source ${PROJECT}/vars
 if [ "${PROJECT}" != "minimal" ]; then
   set +e
   SERVERTIME="$(https_proxy=$HTTPS_PROXY_FULL_URL curl -m 5 -s -I $BROKER_URL_FOR_PREREQ 2>&1 | grep -i -e '^Date: ' | sed -e 's/^Date: //i')"
+  [ -n "$SERVERTIME" ]
   RET=$?
   set -e
   if [ $RET -ne 0 ]; then