Clean up typography CSS output

[jamesmockett]

What are you changing?

• Strips out comment from typography CSS and places semicolons in correct place so they're not rendered if the corresponding property has no value and is not output
• Adds custom Jest matcher to normalise CSS with Lightning CSS and match the result

Why?

• Our snapshot tests are more verbose than they need to be due to the unnecessary output from the typography API
• By normalising the expected and received CSS with a custom matcher we don't need to worry about formatting and whitespace in the tests and can concentrate on the correct properties and values being present

[changeset-bot]

⚠️ No Changeset found

Latest commit: cb61d9e

Merging this PR will not cause a version bump for any packages. If these changes should not result in a new version, you're good to go. If these changes should result in a version bump, you need to add a changeset.

This PR includes no changesets

When changesets are added to this PR, you'll see the packages that this PR includes changesets for and the associated semver types

Click here to learn what changesets are, and how to add one.

Click here if you're a maintainer who wants to add a changeset to this PR