flexibility: temporary core util for refactoring to vanilla css

[EdwardIrby]

resolves #1685

usage

Normal core var import

import {
  layout,
  type,
  motion,
  colorsTextIcon,
  colorsGreen,
  colorsBackgroundDark,
  colorsBorder,
  colorsBackgroundUtility
} from '@pluralsight/ps-design-system-core'

Refactored

import { refactorCssVars} from '@pluralsight/ps-design-system-core'
const {
  layout,
  type,
  motion,
  colorsTextIcon,
  colorsGreen,
  colorsBackgroundDark,
  colorsBorder,
  colorsBackgroundUtility
} = refactorCssVars

We then run a build and now have a css file in our dist directory with the correctly formatted css custom properties and ready for use to do some refactoring on