Shouldn't smoothing of discrete variables be optional in plot_bpv, especially when using kind=t_stat?

[lciti]

Describe the bug

Discrete data passed to plot_bpv are always smoothed:

arviz/arviz/plots/backends/matplotlib/bpvplot.py

Line 90 in 29ca5a1

obs_vals, pp_vals = smooth_data(obs_vals, pp_vals)

I wonder if this should be made optional (possibly default True), at least in the case of kind='t_stat' where one may want to design a custom t_stat function that deals with the discrete data in a particular way. Having the data "smoothed" makes it hard to work with in this case.

[aloctavodia]

Hi, yes. This makes sense.

[Patchouli-Kenntnis]

This makes sense, but can you give me a small example dataset to show the difference of smoothing / without smoothing?