Support other transport layer

[mtsmfm]

Currently, this gem supports only stdio.

For example, vscode-languagesever-node supports:

• stdio
• node-ipc
• named pipe
• socket file

[rmosolgo]

I was hacking on a branch using stdlib TCPServer, would that be useful here?

I pushed my changes: https://github.com/mtsmfm/language_server-protocol-ruby/compare/master...rmosolgo:socket-transport

There's still a big TODO item, and the code isn't too clean, but I thought I'd share in case you're interested in something like that!