Featured product image is not responsive

Describe the bug

Hi, the woocommerce/featured-product block always uses a single background image size even on small viewports.

To reproduce

Steps to reproduce the behavior:

1. Add a featured product block on a page/post
2. view said page/post in frontend
3. inspect the block element in devtools
4. the block uses background-image: url(...);. Therefore the browser cannot select an appropriately sized image for the current viewport size.

Expected behavior

The block should use an <img> or <picture> element w/ appropriate srcset and sizes attributes.

Screenshots

If applicable, add screenshots to help explain your problem.

Environment

WordPress (please complete the following information):

• Core version: 5.8.1
• WooCommerce version: 5.8.0
• WooCommerce Blocks version: bundled w/ woocommerce

Desktop (please complete the following information):

• OS: irrelevant
• Browser irrelevant
• Version irrelevant

Smartphone (please complete the following information):

• Device: irrelevant
• OS: irrelevant
• Browser irrelevant
• Version irrelevant

Additional context

See the core/cover block for an example of how it could be done.