[clang] Reapply "[Analyzer][CFG] Correctly handle rebuilt default arg and default init expression" (PR #127338)

[Nico Weber via cfe-commits]

nico wrote:

> Thanks a lot for report this! 100% agree that we need to find the correct source location. I'm not sure it's the same issue with #123064, I try to find a reproducer.

Sorry, I should've filed an issue with a reproducer. I did so now, #128195. It has a small stand-alone repro.

(Given crashes and bad diag, maybe this should be reverted again until it's a bit more polished?)

https://github.com/llvm/llvm-project/pull/127338