Provide Material You palette as CSS variables

[0neGal]

Describe the feature you'd like
When available, Material You colors should be added as CSS variables, a custom theme can then make use of these to create device specific looks.

Additional context
Ideally these variables would be named something like:

:root {
    --system-accent1-1: ...;
    --system-accent3-100: ...;
    --system-neutral1-900: ...;
    /* and so forth, you get the gist */
}