[libcxx] adds concepts `std::totally_ordered` and `std::totally_ordered_with`

Implements parts of:
    - P0898R3 Standard Library Concepts
    - P1754 Rename concepts to standard_case for C++20, while we still can

Reviewed By: Mordante

Differential Revision: https://reviews.llvm.org/D98983

GitOrigin-RevId: 7959d59028dd126416cdf10dbbd22162922e1336
7 files changed