[libc++] Implements ranges::enable_borrowed_range

This is the initial patch to implement ranges in libc++.

Implements parts of:
- P0896R4 One Ranges Proposal
- P1870 forwarding-range is too subtle
- LWG3379 in several library names is misleading

Reviewed By: ldionne, #libc, cjdb, zoecarver, Quuxplusone

Differential Revision: https://reviews.llvm.org/D90999