Make TlsStream cloneable

[NyxCode]

async_std::net::TcpStream implements Clone, which makes it possible to read and write to a socket at the same time.
Official async-std example
This library does not implement Clone for TlsStream, neither does it implement AsyncRead or AsyncWrite for &TlsStream.
How would I rewrite the example above to use TLS when TlsStream is not clonable?

[abhishekc-sharma]

@yoshuawuyts Correct me if I'm wrong but one of the changes suggested by @NyxCode above would need to be implemented to apply either of the solutions suggested in http-rs/async-h1#74