Add a UI for a template image style on which generated image styles will be based

Problem/Motivation

In an ideal world, we provide an interface like the image styles entity where you can add and configure effects you would like to apply to all generated styles (same as you would apply effects to normal image styles).

Not all effects make sense (like the ones for changing the width/height), but I guess all other effects would be nice. For example, the Image effects → module also provides lots of effects sites might want to add.