[WIP] DEV9: Sockets, allow forwading UDP port for LAN hosting

[TheLastRar]

Description of Changes

Adds the ability to forward UDP ports, and configure Sockets for better compatibility with hosting LAN games

Rationale behind Changes

On Linux, AppImage and flatpak don't properly support pcap
On other platforms, pcap and TAP are harder to configure.
This is an experiment to see if adding additional configuration options to Sockets for LAN is easier than configuring TAP/pcap

Suggested Testing Steps

Using Sockets
On the instance that will be hosting, configure ports in the new "Open Ports" tab in the Network and HDD settings page
Jak X would need port 3658, for other games you would check the logs for ports when attempted connecting to a server.
With a second PC (or a PS2) connect to the hosted game
Experiment to see if LAN mode is needed for a given title

Did you use AI to help find, test, or implement this issue or feature?

No

[prafullpcsx2]

I am trying to get Champions of Norrath online mode working on various devices. It works perfectly between my windows based desktop and laptop both with pcap switch and sockets mode. I have failed to get it working on Macbook though. PCAP doesn't show network adapter. sockets kind of works. I can connect to game server and host a game but it isn't visible to others. When someone else creates a room the room is discovered on the mac but gets stuck on "Doing port discovery" message. I am suspecting it will need port forwarding. Can this PR help with this or is it only for LAN games?

[TheLastRar]

I am trying to get Champions of Norrath online mode working on various devices... Can this PR help with this or is it only for LAN games?

It might help if the game uses a fixed udp port.
Do you know how the game performs port discovery?

[UnstableZero]

Champions of Norrath uses a discovery server (TCP 40801-40804 (regional)) and then binds UDP 3000 for p2p communication. Many users in the community have had to port forward on their router when playing this game. The sequel uses different netcode. Talking to @prafullpcsx2 about this issue, it appears to be isolated to MacOS not allowing them to bind the UDP ports for either game.

[UnstableZero]

@prafullpcsx2 and I resolved their issue. I would assert it was unrelated to this PR.
DNS resolving issues (ISP), and port opening issues (ISP again?). User has seen/will see, expected and known behaviour for the Norrath Server Emulator Project.

Edit: I actually have questions about this PR, at a first glance it appears this could apply to both Champions of Norrath (CON), and Champions: Return to Arms (RTA), as they used different netcode, and have different issues with LAN play. Would this be applicable in cases where patching the default port to something else (ie. 3000 to 3001) is needed? CON uses netcode from the PS2 MMO Everquest, and doesn't support LAN directly. Conversly, RTA uses multiple ports (4000-4004), and an SRS module to fix this issue by sending and attempting both the Pub-IP and the LAN-IP, and with PCAP, times out unless you're fast. Would the LAN mode in this PR affect this behaviour?