There was a bug when the user defines a width on the Image component, but a larger size image is requested.
This is because the browser uses the `srcset` to decide which image size to request and we had the srcset basically hardcoded.
This PR fixes the behavior so that the `srcset` will never be larger than the `width` defined on the component.
It also fixes a bug where the preload srcset did not match the img srcset.
- Related to #18147
- Related to #18122
This PR updates the `<Image>` component to follow the same property naming as native `<img>`.
https://developer.mozilla.org/en-US/docs/Web/HTML/Element/Img#attr-loading
This currently allows two values,`loading=lazy` and `loading=eager`, but there might be new values added in a future spec.
cc @atcastle
