Add observed number of cases into nowcaster outputs

[lsbastos]

Add a column with the observed number of cases in the nowcaster outputs.

> aaa$total
# A tibble: 15 × 7
    Time dt_event   Median    LI    LS   LIb   LSb
   <int> <date>      <dbl> <dbl> <dbl> <dbl> <dbl>
 1    17 2019-10-26    154  154   154    154  154 
 2    18 2019-11-02    173  173   173    173  173 

[rafalopespx]

Now the $data element on the output object from nowcasting_inla returns a grouped by data.frame with a column called observed