Conform to the recommendation in the standard for the socket argument, which is currently `--socket` instead of `--port`

[RobbyCBennett]

Under Implementation Considerations in the LSP spec, the following arguments are laid out as highly recommended ways to standardize the CLI of starting a language server.

LSP:
stdio: (Unclear, but probably the default behavior without the pipe or socket arguments.)
pipe: The pipe / socket file name is passed as the next arg or with --pipe=.
socket: The port is passed as next arg or with --port=.

vscode-languageserver-node:
stdio: --stdio
pipe: --pipe=
socket: --socket=

This repository conforms for stdio and pipe, but not for socket.

[RobbyCBennett]

Alternatively, because VS Code is so popular, we could change the recommendation in the LSP spec to be --socket= instead. The goal of this issue is to make the arguments in the LSP and vscode-languageserver-node consistent.