[Bug]: add warning for age 0 maturity

[Rick-Methot-NOAA]

Describe the solution you would like.

A user with an EWAA model had mature fish occurring at age 0.
It was annual model, with spawn_seas = 1.0 and settlement also at month 1.0.
During the time series, the age 0 fish do not get created until after SSB is calculated, so the SSB does not include any age 0 fish even though they are mature.
During the forecast, the multiple loops cause the age 0 fish to get populated in the first loop and then exist in later loops, so get included in the SSB.
This needs to be detected in the code and a hard warning issued.
@alexjensen-NOAA

Describe alternatives you have considered

none obvious

Statistical validity, if applicable

NA

Describe if this is needed for a management application

yes, upcoming assessment

Additional context

No response

[Rick-Methot-NOAA]

I added an extra write statement to test what is happening with this setup. The N at age 0 is always 0.0 during the time series when SSB is calculated, but during forecast, it is 0.0 in the first ABC_loop, then populated during that loop and that value gets used for the SSB calc for ABCloops 2 and 3. Robust logic to zero this out in each ABC_loop will be tricky because of possibility of multiple seasons and multiple settlement events.

If spawnseason was set to month 2 and recruitment also to month 2, there already is this error message (even without maturity at age 0.0):

Warning 1 Fatal Error! Cannot have spawn_time_seas after beginning of a season and settlements in the same season
++ put spawning at beginning of the season, or move settlements to next season
Also see warning.sso
Exiting SS3!

So, I will add a similar warning with month 1 if age 0 fish are mature. Unfortunately, the existing warning happens in readcontrol, but SS3 does not know at that time if maturity at age 0 is positive or not. So new warning will need to be in prelim calcs.

@iantaylor-NOAA bringing Ian into the discussion