remove print utility

[mitzimorris]

Summary:

The print command has been marked deprecated since 2015 (!).
It needs to be removed because it depends on methods in stansummary_helper.hpp; changing these as part of #1263 breaks print.

Description:

Stan PR stan-dev/stan#3305 introduces a new object, chainset which is easier to deal with than the data structures used by chains. This refactoring made it much easier to implement the computation of split-rank normalized ESS and Rhat, giving separate estimates of for the bulk and tails of the posterior. In order to add these diagnostics to stansummary, it is necessary to use a chainset object everywhere, instead of a chains object. The print utility uses functions stansummary_helper; changes to the function signatures breaks print.

IMO, it's not worth the programming effort to further patch print. Can we remove it in the next release?

Current Version:

v2.35.0

[bob-carpenter]

Agreed. please remove.