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

[Steven Perron via cfe-commits]

https://github.com/s-perron approved this pull request.

This looks good. No major issue. There are a few typos, and a couple smaller issues that we can follow up on in another PR.

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