Color Picker: Integrate inline color boxes

[joaomoreno]

Currently, languages are forced to create decorations in order to have those inline color boxes.

With the new color API, the core should be doing this for them.

[kobenauf]

I agree. For example doing a project with material-ui, the style is in the javascript:

const styleSheet = createStyleSheet({
  App: {
    backgroundColor: '#F0E1D2',
    height: '100%'
  }
})

It would be very helpful to have some way of invoking the color picker for backgroundColor above.