Enable color picker for toml

[vrachels]

similar to enabling the color picker for html in vscode, allow enabling the new color picker for a toml color object.

formats to be discussed, but suggested starting points:
{ r = <0-255>, g = <0-255>, b = <0-255> }
{ r = <0-255>, g = <0-255>, b = <0-255>, a = <0-255> }
{ h = <0-360>, s = <0-100>, l = <0-100> }
{ h = <0-360>, s = <0-100>, l = <0-100>, a = <0.0-1.0> }