add write_checked_* methods to stan::io::serializer

[nhuurre]

Submission Checklist

• [ ] Run unit tests: ./runTests.py src/test/unit
• [X] Run cpplint: make cpplint
• [X] Declare copyright holder and open-source license: see below

Summary

Add new methods to stan::io::serializer that validate the values being written and write NaNs instead if the output does not meet the expected constraints. This helps with stan-dev/stanc3#1163

Intended Effect

How to Verify

Side Effects

Documentation

Copyright and Licensing

Please list the copyright holder for the work you are submitting (this will be you or your assignee, such as a university or company): Copyright holder: Niko Huurre

By submitting this pull request, the copyright holder is agreeing to license the submitted work under the following licenses:

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

[nhuurre]

Irrelevant after closing https://github.com/stan-dev/stanc3/pull/1163.