Update JS Component (image_sizes_extras merge )

I refactored the js component, but need to do some extra work in the service.

I'll continue this after my 8d vacation.

Nice!

woldtwerk → changed the visibility of the branch 3479031-update-js-component to hidden.

@woldtwerk What do you think, should we continue the work? The new JS you showed me in Berlin already looked super promising :) I'd love to see that in before going an 4.0