feat: s2 foundations w/ corner radius

[mrcjhicks]

Description

Motivation and context

Related issue

Types of changes

Patch (bug fixes, typos, mistakes; non-breaking change which fixes an issue)

Minor (add a new token, changing a value, deprecating a token; non-breaking change which adds functionality)

Major (deleting a token, changing token value type, renaming a token by deprecating the old one; fix or feature that would cause existing functionality to change)

Checklist:

I have signed the [Adobe Open Source CLA](https://opensource.adobe.com/cla.html).

I updated the token in all applicable sets. This applies if updating, adding, or deleting a token that has data across different sets (for example, if the value differs across color themes.)

[GarthDB]

@mrcjhicks would we get a diff of any kind? or not, because it's a new data set? I guess it would just compare against the data that is already there, so no change.