register "send to outpaint" on additional tabs

[vladmandic]

Currently this extension creates Send to openOutpaint button on txt2img and img2img tabs Request is to have same button on Extras and PNG info tabs

One example case would be to generate image and save it and then later load it using PNG info and continue with outpainting.

[seijihariki]

Extras tab should be easy. PNG info... need to see, as all until now were gradio galleries.

[vladmandic]

silly workaround is to load using PNG info send to img2img to do inpaininting with nothing masked and then send to openOutpaint - you can see how silly that is :)

[seijihariki]

@vladmandic check testing branch

[vladmandic]

@seijihariki just tried it, works like a charm (both png info and extras tabs) - thanks!