Report if time is not synchronized to the user

### Description

If systemd-timesyncd reports that time is not synchronized we should inform the user that time is (possibly) wrong.

We need to take air gapped systems into account, e.g. if there is no Internet connectivity NTP sync will not be possible, but the time still might be right. Is there information if systemd-timesyncd was able to read the RTC? 🤔 If the RTC reports a seemingly valid time, we should trust it.

### Additional context

_No response_