test: add coverage for string array dgram send()

This commit adds code coverage for dgram's Socket#send() where
the data is an array of strings.
PR-URL: #11247
Reviewed-By: Yuta Hiroto <hello@about-hiroppy.com>
Reviewed-By: James M Snell <jasnell@gmail.com>
Reviewed-By: Michael Dawson <michael_dawson@ca.ibm.com>

Author: cjihrig

test/parallel/test-dgram-send-multi-string-array.js

@@ -0,0 +1,13 @@
+'use strict';
+constcommon=require('../common');
+constassert=require('assert');
+constdgram=require('dgram');
+constsocket=dgram.createSocket('udp4');
+constdata=['foo','bar','baz'];
+
+socket.on('message',common.mustCall((msg,rinfo)=>{
+socket.close();
+assert.deepStrictEqual(msg.toString(),data.join(''));
+}));
+
+socket.bind(()=>socket.send(data,socket.address().port,'localhost'));