title: Firebase Admin SDK apply action code for email verification
body: <p>The Firebase <a href="https://firebase.google.com/docs/auth/custom-email-handler" rel="noreferrer">Customize the Email Action Handler guide</a>
  gives an example of verifying a user's email address on a custom URL to a site hosted through Firebase.</p>
  
  <p>However, I want the custom URL to point to a Firebase cloud function endpoint URL and use admin SDK to verify the oob code instead. But there is no such function as <code>applyActionCode</code> for the <code>admin.auth()</code>.</p>
  
  <p>Is verifying email through a hosted site using javascript the only way to go? I don't really want to expose the code to the browser.</p>