Third-party examples

<!-- Part of the Carbon Language project, under the Apache License v2.0 with LLVM Exceptions. See /LICENSE for license information. SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception -->

This directory contains third-party examples of C++ libraries and how they might be ported to Carbon. The goal is to illustrate both how Carbon works using real-world code as well as relevant and expected steps when migrating from C++ to Carbon.

TODO: Example submodules need to be replaced (issue #1067).