fix: reduce spectrum popover excessive padding

[dsmmcken]

Reduces from ~40px to ~16px. Targets popover dialog only.

Added to styleguide just to be able to preview.

[bmingles]

Unit tests failed due to stylelint error.

Also, looking at the styleguide, I see the CSS variable got updated, but I'm not seeing it impact the padding of the dialog.

Looks like --spectrum-dialog-padding may be the variable that needs to be set

[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 44.59%. Comparing base (9c969f0) to head (dc16689).

Additional details and impacted files

@@           Coverage Diff            @@
##             main    #2530    +/-   ##
========================================
  Coverage   44.59%   44.59%            
========================================
  Files         764      764            
  Lines       42825    42825            
  Branches    10967    10769   -198     
========================================
  Hits        19096    19096            
  Misses      23718    23718            
  Partials       11       11            

Flag	Coverage Δ
unit	44.59% <ø> (ø)

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[dsmmcken]

Looks like --spectrum-dialog-padding may be the variable that needs to be set

ugh, I think copilot "helped" when I re-targeted the class from dialog to popover, it change the variable too for me...

[bmingles]

I verified the padding in the styleguide. Looks good.