Add a "image" property to ImageTexture

[tjw123hh]

Describe the project you are working on

A simple music game

Describe the problem or limitation you are having in your project

I used ImageTexture to store multiple images in a single resource file (in godot 3.x), but now it seems that I can't do this directly in the editor

Describe the feature / enhancement and how it helps to overcome the problem or limitation

It can let me create ImageTexture directly through Image in the editor.

Describe how your proposal will work, with code, pseudo-code, mock-ups, and/or diagrams

If this enhancement will not be used often, can it be worked around with a few lines of script?

Yes.

Is there a reason why this should be core and not an add-on in the asset library?

That's simple and basic.