[clang] [Clang][P1061] Add stuctured binding packs (PR #121417)

[Jason Rice via cfe-commits]

ricejasonf wrote:

>@ricejasonf let us know if you want us to merge on your behalf

@cor3ntin When you think its ready, yes please. I think it requires write access. I fixed the conflict in the ReleaseNotes through Github's UI so that only my feature is under the C++2c features added. I assume other ones were removed as they are for the "previous release".

https://github.com/llvm/llvm-project/pull/121417