Include --source-text-decoration-thickness in preset CSS

[jamesmockett]

What are you changing?

Outputs --source-text-decoration-thickness custom property for each preset based on the font size.

Why?

--source-text-decoration-thickness is used by the <Link> component to apply an appropriate text decoration style for links in the hover state.

[changeset-bot]

⚠️ No Changeset found

Latest commit: a1443ab

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[github-actions]

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[oliverabrahams]

Looks good