refactor(ws client): impl tokio:{AsyncRead, AsyncWrite} for EitherStream (#1249)

* refactor(ws client): tokio:{AsyncRead, AsyncWrite]

Simplify the code by implementing `tokio::io::{AsyncWrite, AsyncRead}`
for the EitherStream.

However, we still need the compat because soketto requires
futures::io::{AsyncRead, AsyncWrite}

* cargo fmt