[Feature]: Signer network HTTP relay implementation

[netrome]

Feature - Signer network HTTP relay implementation

1. Description

Implement the signer network interface with a client that connects to an external HTTP relay, which forwards messages between connected clients.

1.1 Context & Purpose

The HTTP relay implementation is needed to allow separate signer processes running on different hosts to connect to each other and exchange messages.

2.1 Acceptance Criteria:

• There is a HTTP relay service defined which can forward messages between signers.