[libcxx] [llvm] Add C++23 stacktrace (P0881R7) (PR #136528)

[Hristo Hristov via llvm-commits]

Zingam wrote:

@elsteveogrande Thanks for working on this. It's great to see progress on `<stacktrace>`. I took the liberty to assign the issue to you: https://github.com/llvm/llvm-project/issues/105131

Just a few nits: as @frederick-vs-ja pointed out we have a few unwritten conventions for PRs, which while not required strictly is nice to follow for consistency, such as naming PR, and putting relevant info in the commit message, using the github syntax to link PR to issues.
Please mark also implemented/in  progress papers and LWG issues in the status pages found here: https://github.com/llvm/llvm-project/tree/main/libcxx/docs/Status also add an entry for completed papers to Release Notes in https://github.com/llvm/llvm-project/blob/main/libcxx/docs/ReleaseNotes/21.rst


https://github.com/llvm/llvm-project/pull/136528