[flang] [llvm] [Flang][OpenMP][Runtime] Minor Flang runtime for OpenMP AMDGPU (PR #152631)

[via llvm-commits]

agozillon wrote:

Updated the PR stack, the main addition was new RT_OFFLOAD_API_GROUP wrappers in temporary-stack.cpp.

But otherwise I rebased and reformatted the PR to fix the code formatting!

But the PR should address all current comments and pass the CI now, please do feel free to add more comments however if you wish anything further changed! :-)

https://github.com/llvm/llvm-project/pull/152631