message: Allow using more formats per model in thread view
diff: {{cardstack/thread-summary-card thread=thread}}
  <hr>
  {{#each thread.sortedMessages as |message|}}
  - {{#if message.loadedCard}}
  - {{cardstack-content content=message.loadedCard format="card"}}
  - {{/if}}
  + {{#with message.loadedCard as |card|}}
  + {{#with (or message.cardFormat 'card') as |cardFormat|}}
  + {{cardstack-content content=card format=cardFormat}}
  + {{/with}}
  + {{/with}}
  {{/each}}
  <hr>
  <div class="chat-message-pane">
  