[Feature request] Rgba to rgb conversion fuction

function rgbaToRgb(rgbaColor: string, bgColor: string = '#fff') {
  const rgba = parseToRgb(rgbaColor)
  const bg = parseToRgb(bgColor)

  const flattenedColor = {
    red: rgba.alpha * rgba.red + (1 - rgba.alpha) * bg.red,
    green: rgba.alpha * rgba.green + (1 - rgba.alpha) * bg.green,
    blue: rgba.alpha * rgba.blue + (1 - rgba.alpha) * bg.blue,
  }

  return rgbToColorString(flattenedColor)
}

function lightenToOpacity(color: string, opacity: number, bgColor: string = 'white') {
  // ....
}