[libcxx] adds `std::indirectly_readable_traits` to <iterator>

Implements parts of:
    * P0896R4 The One Ranges Proposal
    * LWG3446 `indirectly_readable_traits` ambiguity for types with both `value_type` and `element_type`

Depends on D99141.

Differential Revision: https://reviews.llvm.org/D99461