Image editor - Show frame when setting focal point

[johngrantdev]

When setting the focal point used for generating various images sizes, it would be helpful to be able to see a frame of the crop based on any of the predefined sizes for the upload collection.

I found I needed to do some trial and error when setting the focal point for images that are cropped. This is particularly challenging when using something like s3 as regenerating sharp images after initial generation doesn't seem to work with s3 (a bug?) so I needed to remove the image from the collection and reupload.