Fix product logos in downloads

[janbrasna]

If this changeset needs to go into the FXC codebase, please add the WMO and FXC label. 🤷~ish

One-line summary

Product logos had their parent's box clipped based on font height, this moves the whitespace from outside to inside, to not clip the logo components as the type scale changes…

Significant changes and points to review

There's no change in the box metric with this, with the only exception being it adds a little bottom spacing under the end of every list/section, that I actually find pretty neat. So didn't bother with how to un-collapse whatever is being added there.

This also uses the spacing vars being dynamic across viewports to make the indent smaller on screens that really need to use that space better, so it's moved to a token instead of a fixed size matching the icon in the parent heading exactly.

Issue / Bugzilla link

Fixes #15952

Testing

/firefox/all/ (both desktop and mobile)

[stephaniehobson]

There's a 1 line fix we can port back from springfield ;) https://github.com/mozmeao/springfield/pull/165/files#diff-ae6c70da33562685096d1cc4ffe8baee6c83c21849b152c12fda2eb7bc6f88c9

[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 80.04%. Comparing base (8fe8b99) to head (7c63b7d).
Report is 17 commits behind head on main.

Additional details and impacted files

@@            Coverage Diff             @@
##             main   #16291      +/-   ##
==========================================
- Coverage   80.12%   80.04%   -0.08%     
==========================================
  Files         158      158              
  Lines        8468     8486      +18     
==========================================
+ Hits         6785     6793       +8     
- Misses       1683     1693      +10     

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