fix: multiple connections WITHOUT initial null

[jake-morales]

Improves on #3 by not initializing socket as null.

• Instead, I pass to "useState( )" a function that returns the socket object from "io(...args)".
• Only one socket connection will be made. Since the initial value is a function, it will only be ran once.
• This simplifies the code by eliminating the need for "setSocket"

[focux]

This won't work when doing SSR, it will execute the function in the server and in the client. Creating at least one connection in the server (could be even more) and another one in the client.