[clang] Reapply "[clang] Limit lifetimes of temporaries to the full expression (#170517)" (PR #175816)

[Paul Kirth via cfe-commits]

ilovepi wrote:

> I guess [#175817 (comment)](https://github.com/llvm/llvm-project/pull/175817#discussion_r2817918388) is still pending; is this ready other than that?

Yeah, I'm still puzzling through that bit, but I think this is in reasonable shape otherwise.

https://github.com/llvm/llvm-project/pull/175816