UDP direct outbound with domain name destination is not handled correctly

In general, especially for FAKE-IP usage case, most proxy destination will be replaced with domain name. For a proxy destination, domain name will be resolve remotely. For a direct traffic, the domain name will be resolved by clash-rs. This is trivil for a TCP connection but much subtle for a UDP traffic. When UDP packet is sent, the domain will be resolved too. But when a response packet is received, the src address of this packet is ip, we must map this IP back to domain name to maintain a stable session state.