[Feature propose]
Allow user to pass custom image component to image props in the EuiCard.
The use case is that if a user want to have progressive image loading, it can be simply just pass the custom component to the image props.

One possible approach to achieve this that I could think off is to check the type of the image props and decide whether to render the normal <img /> or the custom component that the user has passed.

I can help out this feature if this proposal is acceptable!