Add Projection specifications

[HarelM]

Launch Checklist

This PR adds the projection specification according to the discussion here:

• Design Proposal: Projection #568

This is still experimental.

The following is how the docs would look like:

• 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.

[codecov-commenter]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 92.60%. Comparing base (139a225) to head (8329fa9).
Report is 81 commits behind head on main.

Additional details and impacted files

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+ Coverage   92.56%   92.60%   +0.03%     
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  Lines        4616     4638      +22     
  Branches     1301     1306       +5     
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+ Hits         4273     4295      +22     
  Misses        343      343              

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[birkskyum]

Is this to be understood as that the provided projection will be the one for low zoom levels, and then web-mercator on high zoom, and we'll add a transition at appropriate zoom levels? If so, and i'm probably overthinking it but better to do so early - do we see upcoming challenges to those assumptions that would favor something more explicit like e.g. a list of zoom-level: projection pairs? Or ability to at disable web-mercator transition, or control when it hits?

[HarelM]

The current implementation of globe transitions from globe to mercator without any zoom configurations or user input, it just does it. I don't know if we can actually keep the globe projection while zooming in further.
Having said that, this is still experimental and I want to be able to use it in the globe branch and see how it behaves and then decide if and how to change it.
CC: @kubapelc

[birkskyum]

That's a good point, as long as it's experimental this will do fine.

[kubapelc]

The current implementation of globe transitions from globe to mercator without any zoom configurations or user input, it just does it. I don't know if we can actually keep the globe projection while zooming in further.

Hi, it needs to do that at a certain zoom level, because otherwise 32 bit floats (or GPU inverse trigonometry) will run out of precision and artifacts will appear.

The transition zoom level (and the animation duration) is currently not configurable, but it is just a few numbers and I don't see any reason why users shouldn't be able to adjust it. The current values (possibly good candidates for default values) make the transition virtually unnoticeable, while the artifacts are also well hidden.