[DevTask] Move object to its own layer and fill the background

[huchenlei]

Stable diffusion can often generate items on undesired location. There is often a need to move the object just slightly on canvas.

Currently the solution would be

• duplicate the layer
• select the object
• reverse select
• delete everything outside selection
• hides the object layer
• generative fill / magic erasor the place where the object used to be

After all these operations, you ended up with the object in its own layer, and can be freely adjusted. This issue is proposing adding a button to streamline those operations to a single click. The proposed workflow would be:

• select the object
• click the button
• pick the desired magic erasor result