[clang] [Clang] Implement C++26’s P2893R3 ‘Variadic friends’ (PR #101448)

[Vlad Serebrennikov via cfe-commits]

Endilll wrote:

Note that there have been additional discussions happening on the new proposed resolution.
https://lists.isocpp.org/core/2024/08/16236.php

https://github.com/llvm/llvm-project/pull/101448