Move all css variables to the html element

[wpears]

With the move to web components and lit in particular, our use of css variables is likely to increase. To ensure variables defined outside components are inherited by them, we should move variable definitions to the html (or :root) element so that they can be inherited by all light and shadow DOM nodes.

[Rishi713144]

I'm interested in contributing to your project

[itsmedavep]

This is partially implemented with the addtion of using w3c design token JSON format tokens in the DS.

Specifically, we now attach all color tokens to :root with an eye to iterating to having all the css custom props in JSON tokens (eg sizing, radii, etc).

What we are still wrestling in the JSON approach is sizing items where we do SCSS math and prefer to that to calc. Regardless, just wanted to update this to reflect the current state.