NVHPC: Add support for NVIDIA HPC SDK compilers based on PGI
- Updated compiler identification for PGI compilers to NVHPC.
- Updated to following modules to reflect the above change:
FindMPI,FindOpenACC, FindOpenMP. - PGI compiler identification remains for older versions of PGI compilers.
Fixes: #20887 (closed)
Topic-rename: nvhpc-compiler