[clang] [llvm] [SPIR-V] Add SPIR-V structurizer (PR #107408)

[Nathan Gauër via cfe-commits]

Keenuts wrote:

Given the ongoing discussion around spirv-sim, I updated all the hlsl tests to be llvm-ir -> SPIR-V tests. All tests now use both FileCheck and spirv-sim. 

https://github.com/llvm/llvm-project/pull/107408