[llvm] [Offload][OMPX] Add the runtime support for multi-dim grid and block (PR #118042)

[Shilei Tian via llvm-commits]

shiltian wrote:

Hmm, something wrong in the AMD part. I tested it on a local NVIDIA GPU and it works. Will take a look.

https://github.com/llvm/llvm-project/pull/118042