Add option to simulate extra data

[Cole-Monnahan-NOAA]

In some cases it can be interesting/informative to compare the fits to the real data to those from simulated data. I.e., how easy it is to identify the real data from 9 other simulated data sets (Buja et al. 2009; https://doi.org/10.1098/rsta.2009.0120).

I propose a new argument to run_osa called simulate which will replace the observed data with simulated ones, given the model expectations.

Then a wrapper can be developed called run_osa_simulator(..., nsims=n) or something like that, which will return n+1 fits for plotting, one being the real data and the other n the simulated data. The user can then quickly visualize how different the real data looks from simulated ones matching the model.

Thoughts?