Add missing checks on unconstraining functions

[WardBrian]

Summary

Unlike e.g. cholesky_factor_free, cholesky_factor_corr_free wasn't checking its inputs. This means that an incorrectly specified user initialization would be silently accepted and unconstrained/reconstrained back to a somewhat arbitrary point, rather than the error every other type provides.

Closes #3380, #3379

Tests

Side Effects

Release notes

Add missing checks to a few unconstraining functions used by initialization.

Checklist

• Copyright holder: Simons Foundation
  The copyright holder is typically you or your assignee, such as a university or company. By submitting this pull request, the copyright holder is agreeing to the 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/)

• the basic tests are passing

  • unit tests pass (to run, use: ./runTests.py test/unit)
  • header checks pass, (make test-headers)
  • dependencies checks pass, (make test-math-dependencies)
  • docs build, (make doxygen)
  • code passes the built in C++ standards checks (make cpplint)

• the code is written in idiomatic C++ and changes are documented in the doxygen

• the new changes are tested