Use strict naming for R internal functions to fix compilation R devl

[r-ash]

This PR switches over to use full names of R internal functions as the short names are now causing compilation errors on development R (4.5.0)

Example failure https://github.com/hivtools/hintr/actions/runs/11897119041/job/33167243470?pr=538#step:6:8176

See the note for Nov 10th https://developer.r-project.org/blosxom.cgi/R-devel

‘R CMD INSTALL’ (and hence ‘check’) now by default compile C++ code with ‘-DR_NO_REMAP’. For the time being this can be reverted by setting environment variable‘R_CXX_USE_NO_REMAP’ to a false value (but that will be removed in the near future).

You can see the compilation failures locally by setting the -DR_NO_REMAP flag locally.

This fixes compilation, but there are a couple of warning still it would be nice to fix.

The only changes here should be prepending R functions with Rf_ (there are some whitespace changes introduced automatically on save, better to review the changes ignoring whitespace)

[jeffeaton]

Thanks for sifting through this; looks good