feat: add auth method for socks proxy

[cxz66666]

tailscale.com/net/socks5 library is a tiny socks5 library, without auth and lack of customization.

Use github.com/armon/go-socks5 instead of it is a good idea, it provides Custom DNS resolution which clearly distinguishes domain and ip, also provide User/Password authentication

[Mythologyli]

感谢贡献！我早上起来细看。 另外，Socks 代理添加密码功能后，应当警示用户 Socks 的安全问题，不应在公网暴露 Socks 服务。密码功能容易造成“这很安全”的错觉。

[Mythologyli]

简单修复了 IPv6 直连失效的问题。准备合并，再次感谢贡献！