[clang] [CIR][AMDGPU][SPIR-V] Implement __builtin_amdgcn_fence (PR #230829)

[Arseniy Obolenskiy via cfe-commits]

aobolensk wrote:

> This conflicts with #225364, which I'm hoping we can merge shortly. If there is additional SPIR-V gap, might it makes sense to base it on top of it?

Let's merge your PR first, I will hold it and rebase after the merge to see if it is still needed

https://github.com/llvm/llvm-project/pull/230829