add vpngate support

[shrinivas17081997]

add option to connect to vpngate.
https://www.vpngate.net/en/

and fetch config from it

and since username is vpn
and password is vpn

just give option to directly connect.

[Ph0rkoz]

It's cool but they log all your traffic.

[ghost]

but sometimes we only need vpn for
unlocking georestricted content
and giving a warning like it keeps log should be enough for the people who dont want vpn with logs.
but its good for those who dont care about logging and its free

[meramsey]

I think what he meant to ask for was native SoftEther VPN protocol support.

Adding Softether native support would be amazing as there is no Linux GUI client for Softether only the CLI.

Adding Softether VPN protocol control would be pretty easy and make this app super popular. Anyone who wanted to then use VPNgate(which uses Softether) could easily do so and lots of providers like myself(Whattheserver.com) and cactusvpn etc all use Softether vpn as the server. Softether supports emulating OpenVPN faster than even openvpn the softether native protocol is faster than them all and would be nice to easily use it via qoumi like we can wireguard and openvpn

an example of some of the Linux CLI way of using softether vpn client for linux is below.
https://www.cactusvpn.com/tutorials/how-to-set-up-softether-vpn-client-on-linux/

Most of the routing stuff that is hard to do is already figured out in the OpenVPN so just wrapping the softether commands in place of the OpenVPN ones would probably be pretty easy. I'm still learning python but I may take a stab at it when I get some free time.

Also if any dev needs an account to test I would happily provide one for free. Ours are logless. I also have a nice writeup and auto-installer which is opensource to rapidly spin up a softether vpn node.

@corrad1nho