Improve mask generation speed

[PladsElsker]

So I found that for large images, gradio takes a significant amount of time JUST to convert images to a format readable by the browser (base64).
The maintainers of gradio won't implement any improvement to this before gradio v4, but they mention a patch here:
gradio-app/gradio#2635 (comment)

I did some tests.
I am getting ~2x faster mask generation for large images (7.2 seconds went down to 3.4 seconds for 2K x 2K images).

I will add this hijack by default in the extension, but I'll add it as a setting thing instead if it creates conflicts with other extensions somehow.
I don't think conflicts are very likely though, so for now the patch is imposed.