feat: The available chatrooms are fetched and displayed in a component

[demos/kafka/chat] / src / app / chatrooms / chatrooms.component.html

<h2>Available Chatrooms</h2>
<ul class="chatrooms">
  <li *ngFor="let chatroom of chatrooms">
    <button type="button">
      <span class="badge">{{chatroom.id}}</span>
      <span class="name">{{chatroom.name}}</span>
    </button>
  </li>
</ul>