[libcxx] [clang] [SemaCXX] Implement CWG2137 (list-initialization from objects of the same type) (PR #77768)

[Mital Ashok via cfe-commits]

MitalAshok wrote:

@cor3ntin It looks like it was in an unrelated file. I've rebased and the format check is passing now

https://github.com/llvm/llvm-project/pull/77768