Move this repository to spacestation13 org

[optimumtact]

Given the wider use of this library by the ss13 community I thought it would be a nice thing to move the repo to spacestation13 where it can better represent it's shared nature.

It's much easier these days with a button to migrate and github maintaing redirections so it's much less likely to break CI across the world.

@tgstation/rust-g-dev-team thoughts?

[ZeWaka]

Everything should be moved fairly cleanly. My only concern is that if the tgstation org forks it or makes a repo named rust-g, that'd break things. I don't really see that happening, though.