Export v8.json file as latest.json in dist folder

[HarelM]

Launch Checklist

• Missing information in spec exported variable #489

This copies the v8.json file into dist/latest.json to allow other libraries to import it and use it.
The exported variable is stripped from the docs and sdk as part of the build to reduce package size.
Fixes #489

I'm not sure this is the best solution to this, but I don't have another one at the moment...

I also improved some of the types while I upgraded maputnik to latest version where I found out about this issue.

• 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.
• Add an entry to CHANGELOG.md under the ## main section.

[HarelM]

In order to import it in maputnik I'll be using the following line:

import latest from '@maplibre/maplibre-gl-style-spec/dist/latest.json'

I think it's OK.

[codecov-commenter]

Codecov Report

All modified and coverable lines are covered by tests ✅

Comparison is base (86c4898) 92.09% compared to head (93726f3) 92.22%.
Report is 12 commits behind head on main.

Additional details and impacted files

@@            Coverage Diff             @@
##             main     #490      +/-   ##
==========================================
+ Coverage   92.09%   92.22%   +0.13%     
==========================================
  Files         100      100              
  Lines        4176     4195      +19     
  Branches     1197     1202       +5     
==========================================
+ Hits         3846     3869      +23     
+ Misses        330      326       -4     

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