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

[Fangrui Song via llvm-commits]

MaskRay wrote:

Related patches have introduced `llvm/lib/CodeGenData` and `llvm/include/llvm/CodeGenData/`. Adding new directories under `llvm/lib` and `llvm/include/llvm` require more discussions.

I think you need to ask more folks about their opinions, my intuition is that reusing `llvm/lib/Object` might be a choice.

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