Update Powerless components to match Color spec updates

[jamesnw]

There have been some color spec updates stemming from this conversation. Given these updates, the Powerless Components section of the CSS Color Level 4, New Color Spaces proposal will need to be updated.

hsl- L no longer makes H or S powerless

If the saturation of an HSL color is 0%, then the hue component is powerless.

lch/oklch- L no longer makes C or H powerless

If the chroma of an Oklch color is 0% or 0, the hue component is powerless. If the lightness of an Oklch color is 0% or 0, or 100% or 1.0, the color will be displayed as black, or white, respectively due to gamut mapping to the display.

lab/ oklab- L no longer makes a and b powerless

If the lightness of an Oklab color is 0% or 0, or 100% or 1.0, the color will be displayed as black, or white, respectively due to gamut mapping to the display.

We may still want to have some way to differentiate the formerly powerless components, but the "display as black or white" appears to be addressed in the gamut mapping algorithm which appears to match the in-progress implementation.

[jamesnw]

Updated to reflect the current state, specifically in hsl, lightness no longer makes any channel powerless.