v4 - Add light-dark() css color function

[oneezy]

This awesome light-dark() css feature just dropped and I wanted to shed some light (or dark) on it to get this integrated into the TW v4 color system! I think this can open up some huge possibilities into styling light/dark modes in one shot while reducing a ton of code!

@endigo9740 at @skeletonlabs has a unique solution for this called Color Pairings which combines the
.{property}-{color}-{baseShade}-{darkShade} together and it feels like the natural next step e.g.:

// html
<LightDark class="bg-blue-50-950" />
<LightDark class="text-blue-50-950" />
<LightDark class="border-blue-50-950" />

What do you guys think?