Image widget must allow for responsive versions.

<!-- Before opening a new issue, please search for duplicate issues to prevent opening a duplicate feature request. If there is already an open existing request, please leave a comment there. --> Prerequisites <!-- MARK COMPLETED ITEMS WITH AN [x] --> • I have searched for similar features requests in both open and closed tickets and cannot find a duplicate. • The feature is still missing in the latest stable version of Elementor ( Elementor Pro. ) What problem is your feature request going to solve? Please describe. It is absolutely essential to be able to serve responsive images, in addition to responsive background images. In today's mobile-first world, sites cannot serve desktop media which is larger, and may include varying art direction considerations, to mobile users. Describe the solution you'd like Allow responsive versions for images. Describe alternatives you've considered Responsive background images are not a sol…