[clang] Reapply "[Clang][CWG1815] Support lifetime extension of temporary created by aggregate initialization using a default member initializer" (PR #97308)

[via cfe-commits]

yronglin wrote:

I split the commits to make the review easier. The 1st commit is the original PR (which just did a simple rebase and resolved conflicts), and the other commits are bug fixes.

https://github.com/llvm/llvm-project/pull/97308