[llvm] [SPIR-V] Add SPIR-V structurizer (PR #97606)

[Natalie Chouinard via llvm-commits]

sudonatalie wrote:

@s-perron, can you do a review of the implementation logic here? I can't remember if you're an llvm committer, but if not I'll do a secondary review and stamp if it looks good to you.

https://github.com/llvm/llvm-project/pull/97606