[llvm] [Bolt] Add a new hidden option to perf2bolt for testing purpose (PR #163785)

[Amir Ayupov via llvm-commits]

https://github.com/aaupov commented:

Thank you for working on this, I think it's useful outside just testing. Please see couple of comments inline.
Additionally, we have `opts::ReadPerfEvents` with a similar purpose and similarly used in testing, can we unify the two options?

https://github.com/llvm/llvm-project/pull/163785