fix(picker): resolve font-style, focus-ring, border issues

[pfulton]

Description

This addresses several issues with the Picker:

• Uses font-style: normal instead of italic for the placeholder
• Fixes an issue where the focus-ring wasn't aligned properly in Express
• Updates the values for a custom property which were causing both Spectrum and Express to have a border-width when Express should not have a border.
• Updates the docs site to add classes to the "switcher" implementations of the Picker so that they'll display properly.

How and where has this been tested?

• How this was tested:
• Browser(s) and OS(s) this was tested with:

Screenshots

To-do list

• 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.
• I have read the CONTRIBUTING document.
• I have tested these changes in Windows High Contrast mode.

• This pull request is ready to merge.

[github-actions]

🚀 Deployed on https://pr-1618--spectrum-css.netlify.app

[Westbrook]

Some questions...

[lunarfusion]

Old focus indicator used box-shadow which can now be removed (lines 190 220, 496, 509, 518, 521).

[Westbrook]

Is this rectangle intended?

1. Go here
2. Click "Select a Country"
3. Press Tab while mouse remains over "Select a Country"

This also show how the quiet Picker has visible UI in non-interactive places. Meaning you can't click the blue line or where the blue line is and get the Picker for focus, nor the rectangle implied by the Blue line.

[Westbrook]

I'm happy to approve this is you'd like, but wanted to get some nits and conceptual questions in front of you before I did.