Use 0 instead of none in OKLCH values

[adamwathan]

This PR updates all of our OKCLH colors to use 0 instead of none due to weird behavior in Chrome where using color-mix with colors using none produces unexpected results:

Both none and 0 behave as expected in Safari and Firefox so suspecting this is a bug in Chrome rather than spec'd behavior.

Fixes #14740

[thecrypticace]

According to the spec Chrome is indeed wrong here (good bit of clipping because the text is lengthy):

… any missing components would be replaced with the value 0.
… classify any missing components in the input colors, … any analogous components … will be carried forward and re-inserted …
The analogous components are as follows: …
Hue H

Hue only ever corresponds to hue and nothing else. So chrome carrying none forward from hue in LCH to the blue channel in sRGB is definitely a bug.

[adamwathan]

Also updated this PR to use in oklch for our color opacity modifier stuff, since that also resolves this issue and feels more correct now that we are using oklch for the default color palette.

I think including both changes makes sense regardless because we want to avoid that Chrome bug either way, and 0 is shorter than none too.