Functions to find first and last date of weather data?

[courtiol]

(Transferred from @LiamDBailey issue in hyenaR)

PROBLEM

Weather data is unavailable for the whole study period. Need functions to find when earliest/latest date of weather data is.

SOLUTION

Something like find_pop_date.weather.first/last()?

We need to make sure to return dates that are 1 day after/before the earliest/latest date time that weather data has been collected because we want to return the date where a full day of weather data was collected.