Channel Support for Networking

[raymondtri]

This PR should be considered blocked by Noxime/steamworks-rs#217 as it is built on a fork

Essentially this exposes several more options so that you can utilize p2p channel functionality

[raymondtri]

Given that this PR (Noxime/steamworks-rs#217) was merged, this implementation should be good to go

One note, if anyone else stumbles across this and wants to save two days, is that steamworks old p2p networking (which is this, which is now deprecated) used to allow networking to yourself.

This has since changed with the new networking_messages and networking_sockets implementations. You cannot p2p to yourself.

I have a public fork of steamworks.js on my profile that has some example implementations of a custom p2p networking intended for co-op where the code is modified so if it is connecting to itself, it does so over a local ip port which does still work with the new model of networking. Feel free to use it if you really need this functionality.

This method is so opinionated however, that I may not merge it back in to this repo. However I still may if I can get a few more things nailed down regarding disconnecting / reconnecting in particular.