[Stan 2.34] Utilize argument save_cmdstan_config

[WardBrian]

Summary:

Added in stan-dev/cmdstan#1204, save_cmdstan_config outputs the arguments provided to cmdstan as a JSON file. This should remove most of the need to parse the CSV comments, besides perhaps for optional validation

[amas0]

Do we want to simply enable this across the board or provide an ability to disable it?

Since this is mostly for internal use, seems like we could just make a one-line change to enable it universally in CmdStanArgs.

[WardBrian]

I’d be in favor of doing it by default