Standardized client interface

[LimpidCrypto]

High Level Overview of Change

This PR adds standardized traits to interact with the websocket clients and future JSON RPC Clients.

• Run MessageHandler::handle_message as task

trait Client

Implements the request logic for each client.

trait AsyncClient

An external trait implemented for T: embedded_io_async::Read + embedded_io_async::Write or T: Stream<Output = String> + Sink<String>. It calls the request implementation of the Client trait.

Context of Change

This is needed for #76 to be able to use std and no_std clients with the high level methods.

Type of Change

• Refactor (non-breaking change that only restructures code)

Test Plan