[libcxx] [llvm] [libc++] Format the code base (PR #74334)

[Louis Dionne via llvm-commits]

ldionne wrote:

I went through everything and this is the set of annotations I'd add for now: https://github.com/llvm/llvm-project/pull/74352. Other suggestions are welcome.

https://github.com/llvm/llvm-project/pull/74334