[llvm] [utils] Add script to generate elaborated assembly tests (PR #89026)

[Fangrui Song via llvm-commits]

MaskRay wrote:

> LG from my point of view, but as noted I think it needs a second pair of eyes.

Thanks. I've made a reply on https://discourse.llvm.org/t/utility-to-generate-elaborated-assembly-ir-tests/78408/6 to encourage other folks can review this patch as well.

https://github.com/llvm/llvm-project/pull/89026