[clang] [llvm] [OpenMP] Move OpenMP implicit argument to the end and reformat (PR #185989)

[Shilei Tian via cfe-commits]

shiltian wrote:

Hmm, the AMDGPU backend has a pass to change the function signature, appending implicit kernel arguments. This will make the `KernelLaunchEnvironment` not always the last one.

https://github.com/llvm/llvm-project/pull/185989