NVIDIA-CUDA: Factor out helper for NVCC C++ standard flags

These standard flags will be the same for other C++-derived languages
supported by nvcc.  Follow the pattern from commit 25439c7d62 (Clang:
Refactor CXX standard flags ..., 2020-03-16, v3.18.0-rc1~362^2~4) to
factor them into a single macro so we can easily reuse them.

Issue: #25143