title: Move coupon form before subtotal in WooCommerce checkout
body: <p>In my Storefront child theme, in the checkout page, I am trying to move the coupon code block just above the cart totals and below the item review
  <a href="https://i.stack.imgur.com/SeYyp.png" rel="nofollow noreferrer"><img src="https://i.stack.imgur.com/SeYyp.png" alt="enter image description here" /></a></p>
  <p>I see in <code>review-order.php</code> that there's the following hook just at the right place:</p>
  <pre><code>do_action( 'woocommerce_review_order_after_cart_contents' );
  </code></pre>
  <p>So in the functions.php file, I added:</p>
  <pre><code>remove_action( 'woocommerce_before_checkout_form', 'woocommerce_checkout_coupon_form', 10 );
  add_action( 'woocommerce_review_order_after_cart_contents', 'woocommerce_checkout_coupon_form' );
  </code></pre>
  <p>But, the coupon block appears twice...and above the order review instead of below.</p>
  <p><a href="https://i.stack.imgur.com/6XuGz.png" rel="nofollow noreferrer"><img src="https://i.stack.imgur.com/6XuGz.png" alt="enter image description here" /></a></p>