[libc++][docs] Add status docs for ranges.

The added documents have two tables: 1 containing links to issues and papers related to ranges. And the other contains most of the sections from the One Ranges Proposal, with their dependencies linked. This will allow us to assign work that can be done in parallel.

Differential Revision: https://reviews.llvm.org/D100393

GitOrigin-RevId: 0f0149b8d3be865d40110780edd79882dfb1dabe
4 files changed