Update: Image Block: Change image by drag & drop an image from the desktop

[jorgefilipecosta]

This PR allows images to dragged into the image block that already contains an image. The new image is uploaded and replace the previous one.

cc: @mtias

How has this been tested?

I added an image block; I selected an image from the media gallery.
I dragged an image from the desktop to the image block created on the previous point.
I verified the image was changed.

[draganescu]

works as advertised! :)

[draganescu]

Awesome update @jorgefilipecosta! Once this #14918 gets approved (by a review) I could add this behaviour to the gallery, media + text, cover, audio, vide and file blocks. Do you think it's ok to enable drag and drop there too?

[jorgefilipecosta]

Thank you for the review @draganescu 👍

I could add this behaviour to the gallery, media + text, cover, audio, vide and file blocks. Do you think it's ok to enable drag and drop there too?

The gallery block already has drag & drop behavior, it appends the dragged images to the gallery, I guess we can leave that behavior.
The cover blocks contain nesting, when we drag an image to a nested area it adds new image block (or gallery) inside that area. Adding drag & drop behavior would collide with the nesting behavior and the result may be uncertain.
The media text also contains nesting but the media element is at the side so I think drag & drop would work well there, and it makes sense to add.
For audio, video and file blocks, it seems like drag & drop to replace totally makes sense, and I'm predicting any potential issue.