Custom layer globe example in ios (#4098)

Exposes some new Projection APIs to help with calculations,
latLndToMercatorXY, worldSize, getLatitudeScale, and
metersPerPixel
Updates `Custom Render Layer` example to render primitives on
globe, ported from mapbox/mapbox-sdk#3860.

cc @mapbox/maps-ios
cc @mapbox/gl-native

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Co-authored-by: Roman Laitarenko <[email protected]>
Co-authored-by: Changelog autocreator bot <[email protected]>
GitOrigin-RevId: c58bd154dd734dc1ebb7bf345d512a052bc8263d

Author: 3 people