title: "no-unused-expressions" with TypeScript 3.7 optional call
body: <p>I'm using TypeScript 3.7 with <code>@typescript-eslint/parser</code> and <code>@typescript-eslint/eslint-plugin</code> for linting.</p>
  
  <p>I'm trying to use optional chaining syntax and it works fine beside <em>optional calls</em>.</p>
  
  <pre class="lang-js prettyprint-override"><code>const { hj } = window;
  hj?.('formSubmitFailed'); // error
  </code></pre>
  
  <p>this gives me an error: <code>eslint(no-unused-expressions)</code></p>
  
  <p>any way to make it work with optional calls?</p>