[clang] [Clang] Implement P0963R3 "Structured binding declaration as a condition" (PR #130228)

[Younan Zhang via cfe-commits]

zyn0217 wrote:

> Hum, do we want to add tests for https://cplusplus.github.io/CWG/issues/2867.html at the same time?

I'll look into that in a followup

https://github.com/llvm/llvm-project/pull/130228