add posterior predictive checks to BSS

[kalebentley]

add posterior predictive check to the most up-to-date BSS model located on the Drano branch (file name "BSS_creel_model_02_2024-04-03.stan")

[tbuehrens]

three things to to do here: 1) add posterior predictive checks from CreelEstimates_publication, 2) add additional PPC for boat likelihood and angler boat likelihoods, 3) add zero inflation from CreelEstimates_publication model, 4) add dummy variable if statement to enable ppl to choose whether to fit zero inflation..,..need for both likelihoods AND generated quantities because affects calculation of daily catch in generated quantities