Support additional normal_id_glm_lpdf signatures

[VisruthSK]

This PR was assisted by ChatGPT.

Submission Checklist

• Run unit tests
• Documentation
  • If a user-facing facing change was made, the documentation PR is here: Reordered normal_id_glm signatures: matrix -> rowvec -> vec, with real then vector y docs#976
  • [] OR, no user-facing changes were made

Release notes

Support row-vector and vector inputs for x in normal_id_glm_lpdf.

Closes #1354.

Copyright and Licensing

By submitting this pull request, the copyright holder is agreeing to
license the submitted work under the BSD 3-clause license (https://opensource.org/licenses/BSD-3-Clause)

[WardBrian]

Also, thanks for doing this!

[VisruthSK]

Of course, been meaning to learn/practice OCaml so I might be making a few more PRs as I see low hanging fruit. Does this merit a doc change btw?

[WardBrian]

I think it would, but it will mostly be a copy/paste job to add more signatures to https://mc-stan.org/docs/functions-reference/unbounded_continuous_distributions.html#index-entry-4436deedaa4adcaf697328f4ab6228f12bf213be

[WardBrian]

Thanks!