`sampling_time` in sample_prior_predictive group attrs

[williambdean]

I'm encountering a slow call to sample_prior_predictive while working with @cetagostini

Currently, some of the samplers add sampling_time to the posterior group. I am suggesting a similar attrs for prior and or prior_predictive groups.

[ricardoV94]

How is that helpful to address the slow sampling time? You may instead want to profile why it's slow with model.profile(model.basic_RVs + model.deterministics). You can also try passing compile_kwargs={mode: "NUMBA"} to prior_predictive in case it's the C backend that's slow