[llvm] [ctx_prof] Add analysis utility to fetch ID of a callsite (PR #104491)

[Mircea Trofin via llvm-commits]

mtrofin wrote:

### Merge activity

* **Aug 20, 1:47 PM EDT**: @mtrofin started a stack merge that includes this pull request via [Graphite](https://app.graphite.dev/github/pr/llvm/llvm-project/104491).


https://github.com/llvm/llvm-project/pull/104491