Asynchrony is not concurrency

"Asynchrony" is a very bad word for this and we already have a very well-defined mathematical one: commutativity. Some operations are commutative (order does not matter: addition, multiplication, etc.), while others are non-commutative (order does matter: subtraction, division, etc.).

    try io.asyncConcurrent(Server.accept, .{server, io});
    io.async(Cient.connect, .{client, io});

Usually, ordering of operations in code is indicated by the line number (first line happens before the second line, and so on), but I understand that this might fly out the window in async code. So, my gut tells me this would be better achieved with the (shudder) `.then(...)` paradigm. It sucks, but better the devil you know than the devil you don't.

As written, `asyncConcurrent(...)` is confusing as shit, and unless you memorize this blog post, you'll have no idea what this code means. I get that Zig (like Rust, which I really like fwiw) is trying all kinds of new hipster things, but half the time they just end up being unintuitive and confusing. Either implement (async-based) commutativity/operation ordering somehow (like Rust's lifetimes maybe?) or just use what people are already used to.