hex method
Returns a Chalk with the foreground color set to the passed in RGB Hex code. This dynamically accepts color hex codes as integer codes (0xAABBCC) or (0xABC) or as strings ('#AABBCC') or ('#ABC')
Implementation
Chalk hex(dynamic hex) {
var rgb = ColorUtils.hex2rgb(hex);
return makeRGBChalk(rgb[0], rgb[1], rgb[2]);
}