[FEATURE] Add Login Networking (similar to FAPI)

[test-tempacc]

Add Fabric API-like login networking

[BluSpring]

I didn't actually think of this when I first made this, I'll have to sit down and think a bit on how to implement this.

[test-tempacc]

I didn't actually think of this when I first made this, I'll have to sit down and think a bit on how to implement this.

Any update on this?

[BluSpring]

Took another quick look and,, oh boy this is gonna be a weird one. We'll see how I can do this while still retaining binary compatibility.

[BluSpring]

Update: I've decided to rewrite the entirety of ModernNetworking's codebase, and I've finally managed to figure out an actual solution to implementing Fabric API style login networking. Additionally, this codebase is now designed to function a lot more in-line with how modern Minecraft does things alongside Fabric API's style of networking.

This will be implemented under the v2 API, and anything relating to the old API will be referred to as v1 and is now unsupported, although I have actually reimplemented all of the v1 API to be able to point back to v2 so we don't break anything that uses the old v1 API.