Product Image block: image is missing loading, srcset, and sizes attributes

[dinhtungdu]

Describe the bug

The image of the Product Image block is missing loading and responsive attributes, which causes some performance issues:

• The image isn't lazy loaded.
• Only one size is loaded regardless of viewport

To reproduce

Steps to reproduce the behavior:

1. Add a Products (Beta) block to a page.
2. Save and check the page on the front end.
3. See <img> element doesn't have loading, srcset, size attribute.