Delay Supervisor start until time has been sychronized (#1360)

* Enable systemd-time-wait-sync.service by default

Enable the systemd-time-wait-sync.service by default. This allows to use
the time-sync.target which allows to make sure services only get started
once the time is synchronized.

* Make sure time is synchronized when starting  hassos-supervisor.service

Use the time-sync.target to make sure that the Supervisor gets stsarted
after the time has been synchronized.

* Set timeout for systemd-time-wait-sync.service

Don't delay startup forever in case time synchronization doesn't work.
This allows to boot the system even without Internet connection.

buildroot-external/rootfs-overlay/etc/systemd/system/systemd-time-wait-sync.service.d/timeout.conf

@@ -0,0 +1,2 @@
+[Service]
+TimeoutStartSec=90s

buildroot-external/rootfs-overlay/usr/lib/systemd/system-preset/70-haos.preset

@@ -1 +1,3 @@
 disable apparmor.service
+
+enable systemd-time-wait-sync.service

buildroot-external/rootfs-overlay/usr/lib/systemd/system/hassos-supervisor.service

@@ -1,8 +1,8 @@
 [Unit]
 Description=HassOS supervisor
 Requires=docker.service rauc.service dbus.service
-Wants=network-online.target hassos-apparmor.service
+Wants=network-online.target hassos-apparmor.service time-sync.target
-After=docker.service rauc.service dbus.service network-online.target
+After=docker.service rauc.service dbus.service network-online.target time-sync.target
 RequiresMountsFor=/mnt/data /mnt/boot /mnt/overlay
 StartLimitIntervalSec=60
 StartLimitBurst=5