Properly wait for time to be picked up from NTP servers in setup

[matgrioni]

After configTime is called, we need to wait for this time to actually be initialized on the device, and so forth for every time we call it. This should be properly done, as opposed to one method I've seen of simply calling getLocalTime which internally waits for the time to be configured.

This can be found referenced in this issue, and also on this page.

[matgrioni]

By default, std::time_t is equal to the uptime. So therefore, once this condition breaks, the time has been synced. This works for setup at least. After waking up from deep sleep, the logic will have to be more difficult, since there will be no baseline, but in either case the idea is the same. When the time has changed, the time has been brought in sync. I should only close this after updating the latest logic to work for all wake-up scenarios not just the latest one. Unfortunately, this logic will not work too well if the time is already accurate, in which case the behavior simply degenerates to the default wait period.

[matgrioni]

There is apparently a sntp_set_time_sync_notification_cb method that already implemented and will most likely be released in the network platform update. This is a callback that is used whenever the time is changed or synchronized. However, for the moment, I will stick with the crude method as it is.