[clang] [clang][CodeGen] Introduce class RawAddress and modify Address in preparation for adding information to it that is needed for pointer authentication (PR #67454)

[Florian Hahn via cfe-commits]

https://github.com/fhahn commented:

It might be helpful for reviewers to add a brief  description to the PR explaining the motivation and implementation

https://github.com/llvm/llvm-project/pull/67454