chore: update javascript for site to account for removal of focus-ring

[mlogsdon18]

Description

Removing the focus-ring polyfill affect some custom JavaScript that we had running on the docs site to add/remove the .is-focused and .is-keyboardFocused classes for certain components. This PR updates that JavaScript to run without the need for the focus-ring class.

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.

• Stepper does not receive focus ring when clicked [@castastrophe]
• Stepper does receive focus ring when tabbed to with the keyboard [@castastrophe]
• Verify that a few other component focus states match the current production site
  • Textfield
  • Combobox
  • Card

Regression testing

Validate:

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

• The page renders correctly
• The page is accessible
• The page is responsive

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

• The page renders correctly
• The page is accessible
• The page is responsive

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. ✨

[github-actions]

🚀 Deployed on https://pr-2102--spectrum-css.netlify.app

[castastrophe]

Looks great!