feat: gap side nav items when icons are present

[mxschll]

Description

Changes spacing between nav items in side nav when icons are present.

Related links, issue #, if available: n/a

How has this been tested?

Locally + Pipeline.

Review checklist

The following items are to be evaluated by the author(s) and the reviewer(s).

Correctness

• Changes include appropriate documentation updates.
• Changes are backward-compatible if not indicated, see CONTRIBUTING.md.
• Changes do not include unsupported browser features, see CONTRIBUTING.md.
• Changes were manually tested for accessibility, see accessibility guidelines.

Security

• If the code handles URLs: all URLs are validated through the checkSafeUrl function.

Testing

• Changes are covered with new/existing unit tests?
• Changes are covered with new/existing integration tests?

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[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 97.61%. Comparing base (90c8d77) to head (a84223c).

Additional details and impacted files

@@           Coverage Diff           @@
##             main    #4831   +/-   ##
=======================================
  Coverage   97.61%   97.61%           
=======================================
  Files         952      952           
  Lines       30816    30820    +4     
  Branches    11318    11318           
=======================================
+ Hits        30081    30085    +4     
- Misses        688      728   +40     
+ Partials       47        7   -40     

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[jkuelz]

Technically, this would be a breaking change because the token was already public and themeable. The impact is likely minimal, but just FYI.

[mxschll]

Yes, did a quick lookup and haven't found usages besides our own. Since it's been quietly introduced recently I think it's ok.