[clang] [llvm] Reapply "[llvm][IR] Extend BranchWeightMetadata to track provenance of weights" (PR #95136)

[Paul Kirth via cfe-commits]

ilovepi wrote:

Still looking into the codegen issue, but I'd expect there's probably just 1-2 cases where I failed to update a pass to use APIs from ProfDataUtils.

https://github.com/llvm/llvm-project/pull/95136