[clang] [clang-tools-extra] [Clang] Reland support friend declarations with a dependent nested-name-specifier (PR #208345)

[Vlad Serebrennikov via cfe-commits]

https://github.com/Endilll commented:

Sorry for being late to the party, but I have several comments about C++ DR tests, and potentially three more green lines for C++ DR status page.

https://github.com/llvm/llvm-project/pull/208345