Convert RadInterpBndryData routines to C++

[maxpkatz]

PR summary

This PR combines the six boundary interpolation routines into one loop. The loop structure is designed in such a way that all six 2D faces are automatically recoverable, even though we write it as if it is 3D.

PR checklist

• test suite needs to be run on this PR
• this PR will change answers in the test suite to more than roundoff level
• all newly-added functions have docstrings as per the coding conventions
• the CHANGES file has been updated, if appropriate
• if appropriate, this change is described in the docs

[zingale]

some test suite failures:
http://groot.astro.sunysb.edu/Castro/test-suite/gfortran/2023-10-30-002/index.html

[maxpkatz]

some test suite failures: http://groot.astro.sunysb.edu/Castro/test-suite/gfortran/2023-10-30-002/index.html

I believe I have resolved this

[zingale]

latest tests: http://groot.astro.sunysb.edu/Castro/test-suite/gfortran/2023-11-01-001/index.html

[zingale]

tests pass: http://groot.astro.sunysb.edu/Castro/test-suite/gfortran/2023-11-02-001/index.html