feat(ui): Extract `lineHeights`

[joe-bell]

Description

Following up on #3535 and chats with @alexcarpenter; this PR extracts lineHeight for self/external reference

Checklist

• [ ] npm test runs as expected.
• [ ] npm run build runs as expected.
• [ ] (If applicable) JSDoc comments have been added or updated for any package exports
• [ ] (If applicable) Documentation has been updated

Type of change

• [ ] 🐛 Bug fix
• [ ] 🌟 New feature
• [ ] 🔨 Breaking change
• [x] 📖 Refactoring / dependency upgrade / documentation
• [ ] other:

[changeset-bot[bot]]

🦋 Changeset detected

Latest commit: 50d6381d98738ed98008cdf8002dbdea00d983e1

The changes in this PR will be included in the next version bump.

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