test: move workqueue tests to correct folder

PR-URL: #262
Reviewed-By: Joyee Cheung <[email protected]>

Author: mmarchini

test/workqueue-test.js test/plugin/workqueue-test.jstest/workqueue-test.js renamed to test/plugin/workqueue-test.js

@@ -2,7 +2,7 @@
 
 const tape = require('tape');
 
-const common = require('./common');
+const common = require('../common');
 
 function testWorkqueueCommands(t, sess) {
   sess.send('v8 getactivehandles');