refactor!: remove `insim::connection`, move various other components

[theangryangel]

• remove insim::connection as discovered under #127 its not helping much is just adding more layers of wrapping in upstream crates/projects
• rename insim::network to insim::net to more closely align with std library
• move insim::codec to within net
• add convenience aliases to root of crate
• add websocket feature to disable tungstenite
• Rename Network trait to TryReadWriteBytes to better indicate it's intended usage. Network was too generic
• Move race_directord to it's own repo

Fixes #127