Replace additional spread operator usage

[neodescis]

Launch Checklist

Removes one final usage of the object spread operator that is still making its way to the MapLibre GL worker thread bundle. This usage is more difficult to hit than others already fixed for the original issue maplibre/maplibre-gl-js#6429.

• Confirm your changes do not include backports from Mapbox projects (unless with compliant license) - if you are not sure about this, please ask!
• Briefly describe the changes in this PR.
• Link to related issues.
• Include before/after visuals or gifs if this PR includes visual changes.
• Write tests for all new functionality.
• Document any changes to public APIs.
• Post benchmark scores.
• Add an entry to CHANGELOG.md under the ## main section.

[codecov-commenter]

Codecov Report

❌ Patch coverage is 0% with 1 line in your changes missing coverage. Please review.
✅ Project coverage is 95.37%. Comparing base (8dc8c06) to head (af1d7b6).

Files with missing lines	Patch %	Lines
src/validate_style.min.ts	0.00%	1 Missing ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##             main    #1297      +/-   ##
==========================================
+ Coverage   95.33%   95.37%   +0.03%     
==========================================
  Files         114      114              
  Lines        7401     7398       -3     
  Branches     2245     2327      +82     
==========================================
  Hits         7056     7056              
+ Misses        345      342       -3     

☔ View full report in Codecov by Sentry.
📢 Have feedback on the report? Share it here.

🚀 New features to boost your workflow:

• ❄️ Test Analytics: Detect flaky tests, report on failures, and find test suite problems.
• 📦 JS Bundle Analysis: Save yourself from yourself by tracking and limiting bundle sizes in JS merges.

[neodescis]

@HarelM, is there a reason to restrict usage of Object.assign()? I didn't notice it was disallowed until creating the PR, but it seems like the natural substitution for the spread operator.

[HarelM]

Might be a security thing or that we wanted to use spread operator more.
Feel free to to change the relevant lint rule.

[neodescis]

Alright, the lint restriction is removed. I think this should be good to go. Given the difficulty of hitting this one, probably there's no hurry to release and incorporate it into MapLibre GL, but let me know if you disagree. I'm happy to create a PR there to bump the dependency if you like.