This I/O object wraps an ordinary socket and provides a built-in
timeout and optional bandwidth rate-limiting facility.
Added class template basic_stream_socket
* Meets the requirements of AsyncReadStream and AsyncWriteStream
* Partially supports P1322R0:
"Networking TS enhancement to enable custom I/O executors"
http://www.open-std.org/jtc1/sc22/wg21/docs/papers/2018/p1322r0.html
A strand or other io_context-compatible executor may be
chosen to use for all asynchronous stream operations.
* Supports independent timeouts on logical operations:
connect, read, write, or both read and write.
* Provides an option for a configurable rate limit
limit on the maximum rates of reading or writing.
* The previous experimental implementation,
`timeout_socket` and related types, is removed.
* stream_socket is an alias for basic_stream_socket which
uses `net::ip::tcp` as its protocol.