Use String Types For node `dgram.createSocket` Type

[mjbvz]

From https://github.com/Microsoft/vscode/issues/27160

Current signature of node's dgram.createSocket is:

    export function createSocket(type: string, callback?: (msg: Buffer, rinfo: RemoteInfo) => void): Socket;

Type should be restricted to the strings 'udp4' or 'udp6'

[mjbvz]

Sorry, wrong repo