[libc++] add zip_view and views::zip for C++23

- add zip_view and views::zip for C++23
- added unit tests
- implemented section 5.6 (zip) in P2321R2

I used clang-format to format the files but they look nothing like the rest of the code base. Manually indenting each line to match the styles sounds like an impossible task. Is there any clang-format file which can format it reasonable similar to the rest of the code base so that I can manually format the rest lines that look weird?

Reviewed By: ldionne, #libc, philnik, var-const

Spies: Mordante, philnik, libcxx-commits, mgorny

Differential Revision: https://reviews.llvm.org/D122806