refactor(net): introduce channel and refactor TCP

[wangrunji0408]

• add deliver method to Socket trait. let NetSim take care of message delivery
• introduce BindGuard to auto release a bound port on drop
• introduce channel as a reliable and ordered transport over the network
• refactor TCP implementation using channel

Seems that the new Rust toolchain introduced several clippy rules which generate warnings in prost crate. We'll ignore the failure of clippy task.