[clang] [clang][dataflow] Add synthetic fields to `RecordStorageLocation` (PR #73860)

[Gábor Horváth via cfe-commits]

https://github.com/Xazax-hun commented:

I generally love this direction, this was just a first pass, not a full review. I plan to take a second look but wanted to familiarize myself with the PR and start some conversations.

https://github.com/llvm/llvm-project/pull/73860