Network management UI: add system proxy default TUN Mode

[atlantis451]

• System proxy: TUN Mode
  It means create a "virtual network adapter".
  Working Principle
  All traffic passes through tor SOCKS(and self-hosted SOCKS)
  All traffic passes through i2p http (and self-hosted http)

steps

1. Network management UI create a "virtual network adapter".
   
2. input proxy tor SOCKS 127.0.0.1:9150

TUN "virtual network adapter". ip 127.0.0.1 port 9150

Network management UI added option TUN
TUN acts as an agent for existing agreements, HTTP proxy HTTPS proxy SOCKS proxy
Use TUN mode to proxy all traffic throughout the system, including terminals

Why this request?
I’m in a country where the internet is very blocked, and upgrading MidnightBSD or downloading software is a hassle, github gitlab Ping over time 300ms.

There are hundreds of millions of users in China, Iran, the Middle East, etc., who need this feature, and they're still using Win10, etc., and the most important reason is because of proxy

In thousands of Linux and BSD distributions, there is no single system desktop environment that proxies all traffic,
I use a proxychains and it’s a terrible proxy for the terminal, very slow.