Implement legacyCSS option

[elchininet]

This pull request implements a new option for the class instantiation and the static methods. legacyCSS, if this option is true, css output will be in CSS Level 3, otherwise it will be CSS Level 4. If the option is not provided the library tries to extract this iformation from the color provided.

ColorTranslator.toHSLA('rgb(255 0 255)'); // hsl(300 100% 50% / 1)
ColorTranslator.toHSLA('rgb(255,0,255)'); // hsla(300,100%,50%,1)
ColorTranslator.toHSLA(
    'rgb(255 0 255)',
    { legacyCSS: true }
); // hsla(300,100%,50%,1)