update options for laplace

[SteveBronder]

Summary

A few small changes for the laplace docs. We use a tuple for the options now

Copyright and Licensing

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• Code: BSD 3-clause (https://opensource.org/licenses/BSD-3-Clause)
• Documentation: CC BY-ND 4.0 (https://creativecommons.org/licenses/by-nd/4.0/)

[avehtari]

I commented this in Stan gathering, but adding here for the record. I think it would be good to have hessian_block_size as main level argument in both laplace_marginal and laplace_marginal_tol. It is essential part of the likelihood Hessian computation, and if user forgets to set it when it needs to be larger than 1, user gets wrong results without any warning. Having it as explicit argument near likelihood function, would mean the user would need to at least explicitly set it in order to be able to use Laplace method. This would also reduce the need to use laplace_marginal_tol.

[avehtari]

in which branch I can find generate_laplace_options? I did run make stan-update in cmdstan, but stanc still doesn't know about the new function