Support a no-IO feature

[Zk2u]

In some cases, we can't run Tokio in the current environment for either the client or the server.

This issue tracks the separation of HardLight's core state machine and logic from the networking IO stack which is currently using Tokio and tungstenite. This will allow developers to handle their own networking, providing just Vec per incoming message. This means HardLight can delegate its IO to the application and handle server and client logic internally as usual.