[UI v2] chore: Removes toggleVariants as an export

[devinvillarosa]

Exporting this would give an eslint warning (which shows up in all UI related PRs).
Separating the variants into another file for now and exporting it through an index.ts file

If needed, we can move toggleVariant as its own file and import/export it from there

Checklist

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Relates to #15512