chore(alertdialog): adds custom tokens

[jenndiaz]

Description

Adds custom tokens needed for Alert Dialog #1862

--spectrum-alert-dialog-padding
--spectrum-alert-dialog-description-to-buttons

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.

There should be no UI changes!

Regression testing

Validate:

1. A legacy documentation page (such as accordion), including:

• The page renders correctly [@castastrophe]
• The page is accessible [@castastrophe]
• The page is responsive [@castastrophe]

2. A migrated documentation page (such as action group), including:

• The page renders correctly [@castastrophe]
• The page is accessible [@castastrophe]
• The page is responsive [@castastrophe]

To-do list

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

[castastrophe]

Code looks great, just waiting on the PR checks to finish. @jenndiaz there's no small sizing correct?

[github-actions]

🚀 Deployed on https://pr-2101--spectrum-css.netlify.app

[jenndiaz]

@castastrophe correct no small sizing, in this case Medium is Desktop and Large is Mobile.