Add boot/00-check-rtc-and-wait-ntp.sh to cidata

In vz, the VM lacks an RTC when booting with a kernel image (see: https://developer.apple.com/forums/thread/760344).
This causes incorrect system time until NTP synchronizes it, leading to TLS errors.
To avoid TLS errors, this script waits for NTP synchronization if RTC is unavailable.

This script does the following:
- Exits with 0 if `/dev/rtc0` exists.
- Exits with 0 if `systemctl` is not available.
- Enables `systemd-time-wait-sync.service` to wait for NTP synchronization at an earlier stage on subsequent boots.
- Waits for NTP synchronization within the script for the first boot.

Log output during execution:
```console
LIMA 2024-08-08T23:51:15+09:00| Executing /mnt/lima-cidata/boot/00-check-rtc-and-wait-ntp.sh
Created symlink /etc/systemd/system/sysinit.target.wants/systemd-time-wait-sync.service → /usr/lib/systemd/system/systemd-time-wait-sync.service.
TimeUSec=Thu 2024-08-08 23:51:15 JST, Waiting for NTP synchronization...
TimeUSec=Thu 2024-08-08 23:51:16 JST, Waiting for NTP synchronization...
...
TimeUSec=Thu 2024-08-08 23:51:41 JST, Waiting for NTP synchronization...
TimeUSec=Thu 2024-08-08 23:51:42 JST, Waiting for NTP synchronization...
TimeUSec=Tue 2024-11-12 11:43:37 JST, NTP synchronization complete.
NTPMessage={ Leap=0, Version=4, Mode=4, Stratum=2, Precision=-25, RootDelay=991us, RootDispersion=259us, Reference=11FD1CFB, OriginateTimestamp=Thu 2024-08-08 23:51:43 JST, ReceiveTimestamp=Tue 2024-11-12 11:43:36 JST, TransmitTimestamp=Tue 2024-11-12 11:43:36 JST, DestinationTimestamp=Thu 2024-08-08 23:51:43 JST, Ignored=no, PacketCount=1, Jitter=0 }
```

Signed-off-by: Norio Nomura <norio.nomura@gmail.com>

Author: norio-nomura

pkg/cidata/cidata.TEMPLATE.d/boot/00-check-rtc-and-wait-ntp.sh

@@ -0,0 +1,25 @@
+#!/bin/sh
+set -eu
+
+# In vz, the VM lacks an RTC when booting with a kernel image (see: https://developer.apple.com/forums/thread/760344).
+# This causes incorrect system time until NTP synchronizes it, leading to TLS errors.
+# To avoid TLS errors, this script waits for NTP synchronization if RTC is unavailable.
+test ! -c /dev/rtc0 || exit 0
+
+# This script is intended for services running with systemd.
+command -v systemctl >/dev/null 2>&1 || exit 0
+
+# Enable `systemd-time-wait-sync.service` to wait for NTP synchronization at an earlier stage.
+systemctl enable systemd-time-wait-sync.service
+
+# For the first boot, where the above setting is not yet active, wait for NTP synchronization here.
+until ntp_synchronized=$(timedatectl show --property=NTPSynchronized --value) && [ "${ntp_synchronized}" = "yes" ]; do
+	time_usec=$(timedatectl show --property=TimeUSec)
+	echo "${time_usec}, Waiting for NTP synchronization..."
+	sleep 1
+done
+# Print the result of NTP synchronization
+ntp_message=$(timedatectl show-timesync --property=NTPMessage)
+time_usec=$(timedatectl show --property=TimeUSec)
+echo "${time_usec}, NTP synchronization complete."
+echo "${ntp_message}"