[clang] [OpenMP] Improve omp offload profiler (PR #68016)

[via cfe-commits]

fel-cab wrote:

I have prepared a presentation to better explain the proposed changes
https://docs.google.com/presentation/d/1lLlR7g29MWidaX9BLCUaKZhdvN-dphUE2BGMXhZCIoA/edit?usp=sharing

https://github.com/llvm/llvm-project/pull/68016