Save / restore current time to / from flash

Feature request (if it makes sense)

If NTP enabled & NTP configured & NTP updated_since_last_powerup   
  If WiFi_just_went_down 
    Store current date/timestamp to flash / permanent memory

@ Power up, during flash reload:
If date/timestamp NOT Null
  Load date/timestamp from flash

This way, WLED has a date/time stamp that is at least close even if NTP is unavailable (internet connection failed), but power is still available.

If it’s way off, people will understand. However, for a brief power outage followed by a prolonged internet outage, most time-based automation configured in WLED will still operate relatively close to the right time/date.

This might be a WLED 2.0 feature, but throwing it out there as people are gearing up for fall and winter outdoor light shows and automations, in case it is super easy to do and there is available flash storage for it.

Comments welcome by anyone, especially anyone with better ideas.