Lightyear UDP Transport

This crate provides a UDP transport layer for Lightyear. It defines UdpIo which uses std::net::UdpSocket for sending and receiving raw byte payloads over UDP. This is a common and often preferred transport for real-time games due to its low overhead.

The UdpPlugin integrates this transport into a Bevy application, managing the lifecycle of UDP sockets and handling the IO operations in conjunction with Lightyear's Link component.

It also includes server-specific UDP IO handling when the "server" feature is enabled.