[css-color-6] color-contrast() should allow specifying multiple contrast algorithms that need to be satisfied #7357
Description
Assuming we can specify the contrast algorithm at all (see #7356), we should be able to specify multiple of them as a safeguard for algorithm bugs, as well as to satisfy legal constraints.
E.g. we know that WCAG 2.1 contrast is severely broken, yet it is legally mandated that websites pass it. Once we have a better contrast algorithm, we may want color-contrast() to find us a color pair that both satisfies WCAG 2.1, as well as the new improved algorithm.
Syntax could just be a space-separated list of contrast algorithms.
(Issue filed following breakout discussions between @svgeesus, @fantasai, @argyleink and myself)