[clang] [libcxx] [Clang] Implement CWG2137 (list-initialization from objects of the same type) (PR #94355)

[Yaxun Liu via cfe-commits]

yxsamliu wrote:

> @yxsamliu Re: [#77768 (comment)](https://github.com/llvm/llvm-project/pull/77768#issuecomment-1957171805): That is the expected behaviour, since CWG2137 expressly wants to use initializer_list constructors over non-initializer_list constructors (especially copy constructors)

Agreed. We will fix on app side.

Do you have a plan to reland this PR since we have a library hipDF depending on it. Thanks.

https://github.com/llvm/llvm-project/pull/94355