Better tile level of detail for alternate projections

[mourner]

Closes #11233 by adjusting tile LoD based on the ratio of area of a reprojected tile to the original mercator one. This seems to improve contrived cases where lower zoom tiles aren't split until you zoom way in.

Still needs extensive testing. I believe there are some bugs in the LoD code that are unrelated but can lead to very weird loading situations.

Launch Checklist

• briefly describe the changes in this PR
• include before/after visuals or gifs if this PR includes visual changes
• write tests for all new functionality
• post benchmark scores
• manually test the debug page
• apply changelog label ('bug', 'feature', 'docs', etc) or use the label 'skip changelog'
• add an entry inside this element for inclusion in the mapbox-gl-js changelog: <changelog></changelog>

[arindam1993]

does this fix this too? 👀
#11244

[mourner]

@arindam1993 nope, just checked — my fix mostly affects low zoom levels, there must be something else going on on the higher ones.

[ansis]

This works great. It handles the lowest zoom levels much better in the conic projections.

How should we test LOD tile loading? Would render tests with geojson sources + tile debug boundaries enabled work well enough? I think really thorough coverage here is important because there are so many situations + projections. And other bugs whose fixes could affect this in unexpected ways.