title: Checking for default values in Typescript
body: <p>Is there any way in typescript / typescript-eslint to render an error when an optional parameter does not have a a default value? I am trying to convert my React codebase from JSX to TSX and no longer having the warnings about not having <code>defaultProps</code> defined is worrisome. Thanks.</p>
  
  <p><strong>bad: title does not have default prop value</strong></p>
  
  <pre><code>import * as React from 'react';
  
  interface Props {
    title?: string;
  }
  
  const SampleComponent: React.FC&lt;Props&gt; = ({ title }) =&gt; (
    &lt;h1&gt;
      {title &amp;&amp; &lt;p&gt;{title}&lt;/p&gt;}
    &lt;/h1&gt;
  );
  
  export default SampleComponent;
  </code></pre>
  
  <p><strong>good: title has default prop value</strong></p>
  
  <pre><code>import * as React from 'react';
  
  interface Props {
    title?: string;
  }
  
  const SampleComponent: React.FC&lt;Props&gt; = ({ title = 'foo' }) =&gt; (
    &lt;h1&gt;
      {title &amp;&amp; &lt;p&gt;{title}&lt;/p&gt;}
    &lt;/h1&gt;
  );
  
  export default SampleComponent;
  </code></pre>