[clang] [Clang][Sema] Implement approved resolution for CWG2858 (PR #88042)

[via cfe-commits]

cor3ntin wrote:

This needs a release note and a test in test/CXX/drs/dr28xx.cpp (and a rerun of www/make_cxx_dr_status )

https://github.com/llvm/llvm-project/pull/88042