[feature request] connection reuse and forwarding traffic to a SOCKS5 proxy

[ZhiShengYuan]

1. Implement Connection Reuse:
   Currently, we encounter SSL handshake rejections due to fast connection handshakes, resulting in decreased speed and a poor user experience. While MUX partially addresses this issue, it introduces speed problems. To improve this, we suggest implementing connection reuse by enhancing the trojan protocol. This involves adding a command to signal the end of the current connection and keeping it in a connection pool for future use. Additionally, implementing a mechanism to periodically check connection status would ensure stability, especially in situations like NAT session deletion or receiving a reset.

2. Support Forwarding Traffic to a SOCKS5 Proxy:
   In certain scenarios, using the server that accepts the handshake as the outbound traffic server is undesirable, particularly when the server IP is not clean, and may cause restricting access to specific websites(Currently, Netflix restricts access based on client IP addresses. However, it would be beneficial to also support traffic forwarding to a SOCKS5 server. This would enable users to leverage V2Ray's capabilities for sniffing and making routing decisions based on domain names.
   ). However, forwarding all traffic to the backend server can create a heavy load. To address this, we propose adding support for a SOCKS5 client to selectively proxy traffic, excluding shadow-TLS handshake traffic. This would offer flexibility in routing traffic, load balancing, and maintaining network integrity.