chore(typography): add fallback sizes for testing

[castastrophe]

Description

In the Typography storybook, allow typography elements to gracefully fallback to the next closest size when an invalid size is provided.

How and where has this been tested?

Please tag yourself on the tests you've marked complete to confirm the tests have been run by someone other than the author.

Validation steps

Visit the typography storybook page here:

• @pfulton At the extra-extra-small size, expect the spectrum-Body and spectrum-Code snippets to use the sizeXS class.
• @pfulton At the extra-small size, expect the spectrum-Detail snippet to use the sizeS class.
• @pfulton At the extra-extra-large size, expect the spectrum-Detail and spectrum-Code snippets to use the sizeXL class.
• @pfulton At the extra-extra-extra-large size, expect the spectrum-Detail and spectrum-Code snippets to use the sizeXL class.
• Expect to see updates to VRT baselines for typography sizing.

Regression testing

Validate:

1. The documentation pages for at least two other components are still loading, including:

• The pages render correctly, are accessible, and are responsive.

2. If components have been modified, VRTs have been run on this branch:

• VRTs have been run and looked at.
• Any VRT changes have been accepted (by reviewer and/or PR author), or there are no changes.

To-do list

• I have read the contribution guidelines.
• I have updated relevant storybook stories and templates.
• If my change impacts other components, I have tested to make sure they don't break.
• ✨ This pull request is ready to merge. ✨

[changeset-bot]

⚠️ No Changeset found

Latest commit: 8f35a00

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[github-actions]

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Summary

Total size: 4.31 MB^*

🎉 No changes detected in any packages

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* Results are not gzipped or minified.
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[pfulton]

Looks good!