So the closest thing I could find is the “3PointLevels”. Sadly it’s a bit counterintuitive, e.g. you have to use input values <0 for black and >1 for white to achieve the effect described above.
EDIT: A better way at least seems to be setting black value to 0, white to 1, middle value between 0 and 1, and also connect the middle point with a value 0…1