Initial support for gradient support for text color
https://files.facepunch.com/ognik/1b1611b1/2022-01-02_52-09-a8c40adc-c3b1-47ac-8239-9887f8341be7-6vjTyEYW.png
```css
color: linear-gradient( rgba(255,0,0,1), rgba(255,154,0,1), rgba(208,222,33,1), rgba(79,220,74,1), rgba(63,218,216,1), rgba(47,201,226,1), rgba(28,127,238,1), rgba(95,21,242,1), rgba(186,12,248,1), rgba(251,7,217,1), rgba(255,0,0,1) );
text-background: linear-gradient( red, green );
text-background-image: linear-gradient( pink, blue );
```