message: fix: use panel component for developer apps
diff: {{title (t 'settings.developer-apps.title')}}
  -<div class='panel panel-default'>
  - <div class='panel-heading clearfix'>
  - <h3 class='panel-title'>{{t 'settings.developer-apps.title'}}</h3>
  - </div>
  - <div class='panel-body'>
  +<Panel as |panel|>
  + <panel.heading @title={{t 'settings.developer-apps.title'}} />
  + <panel.body>
  {{outlet}}
  - </div>
  -</div>
  + </panel.body>
  +</Panel>
  