Interface Contrast Preference

[jameskoster]

One part of the color scale work (#53612) worth extracting for separate discussion is an “Interface contrast” user preference.

The current color scale is highly prescriptive about which values components should use based around the objective of meeting WCAG AA guidelines. This is a solid default/foundation that should be reflected in the new scale, but it also dismisses large segments of the ability spectrum (for instance those who require a AAA compatible UI).

A preference for contrast can help individual users create a subjectively comfortable appearance.

What would be the best way to implement this, if it is agreed that the idea has merit? Should there be a dedicated ui-element-border variable the value of which is conditional based in the users contrast preference? Should it be a property of the Theme component? Something else? Let's discuss.

cc @WordPress/gutenberg-design

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Note: The mockup above is a rough sketch, not a proposal.

[jasmussen]

Rather than a slider, I think we should curate the three options with presets.

Can the default center option be made identical to what the componentry looks like today?