[llvm] Reland [CGData] llvm-cgdata #89884 (PR #101461)

[Fangrui Song via llvm-commits]

MaskRay wrote:

> @aemerson Thank you for reviewing RFC and unblocking this PR!
> 
> > currently llvm/lib/CodeGenData/, which I feel a bit confusing when llvm/lib/CodeGenTypes/ is present
> 
> @MaskRay What about `CGData` or something else to avoid this confusion? This library name also seems more consistent to the tool name, `llvm-cgdata`.

`llvm/lib/CGData` looks good to me (analogy: ObjCopy for llvm-objcopy).

https://github.com/llvm/llvm-project/pull/101461