[llvm] [PassManager] Add pretty stack frames (PR #96078)

[Arthur Eubanks via llvm-commits]

aeubanks wrote:

> > I would have liked to print the pipeline string instead of pass name (so we also get pass options), but the necessary information for that doesn't seem to be available.
> 
> I just realized that this _is_ available via PI -> PIC, just currently not exposed in the API. I think I'll change this PR to make use of that.

It's only available when `shouldPopulateClassToPassNames()` is true, unsure of the compile time impact of always populating the pass name map

https://github.com/llvm/llvm-project/pull/96078