Push image_style_options() global function to a service

Through creating a custom formatter, I found that image_style_options() remains in image.module.

If my understanding of the D8+ environment is correct, this would be better suited as a service. A global function that does not implement a hook — seems to be an artifact of the D7 days.

There would need to be changes in both the image and responsive_image core modules for this to happen. Throwing a deprecation warning for the functional approach would be the next logical step.

Is there a reason I'm not privy to for the continued functional approach?