Merge topic 'AppleClang-c++26'

47924bd1ba AppleClang: Add C++26 support
f2b45d8326 ci: Record expected C++26 support in Debian jobs

Acked-by: Kitware Robot <kwrobot@kitware.com>
Acked-by: Nico Weber <thakis@chromium.org>
Merge-request: !11572