Add outbound tag to tun

Add outbound tag to tun to allow outbound connection go into that tun device 

Combined with bridge/portal (reverse proxy), packet to other processes in the operating system  can come out from tun  with the tun ip instead of  127.0.0.1 when using direct. This will simulate a proper incoming ip for UDP packets, as if it's coming from a real VPN network, making some program like WebRTC happy.