Add a drop zone to the rendered image in the Image block

[richtabor]

Is your feature request related to a problem? Please describe.
I should be able to drag an image file and drop it over an uploaded image in the Image block to easily replace the current image.

Describe the solution you'd like
When I drag an image file over an existing image, the drop zone should appear where I can drop the new image to upload. Upon releasing the file, the rendered image is replaced with the image file I dropped in.

Once learned, this experience would make switching out images within the Image block much easier to do, requiring just one action - instead of selecting on the block, clicking the "Edit image" toolbar control, then dragging in an image.

[swissspidy]

This already exists since #14983

[richtabor]

Sweet!