title: Apply list style for botframework v4 choice prompt: NodeJS
body: <p>Hi I'm trying to add a list style in the choices of botbuilder-dialog; Botframework v4, NodeJS.</p>
  
  <p>I'm trying to implement it using the code below, but its seems that the list style does not take any effect in the choices. It should prompt a numbered list but it prompts a button like list. </p>
  
  <pre><code>const{ChoicePrompt, ListStyle} = require('botbuilder-dialogs');
  const CHOICE_PROMPT = 'CHOICE_PROMPT';
  
  //Set up ChoicePrompt
  var cp = new ChoicePrompt(CHOICE_PROMPT);
  cp.Style = ListStyle.list;
  this.addDialog(cp);
  
  this.choicesX = ['Pick1', 'Pick2', 'Pick3'];
  
  
  //function
  async test(stepContext){
      return await stepContext.prompt(CHOICE_PROMPT, {
          prompt: 'Select item:',
          choices: this.choicesX
      });
  }
  </code></pre>
  
  <p>What is the correct way to add a list style in the choices of choice prompt?</p>