Expose EPSG:3857 projection calculation utils

[LukasPaczos]

Capturing from https://github.com/mapbox/mapbox-gl-js/issues/9998#issuecomment-705693893 and https://github.com/mapbox/mapbox-navigation-android/pull/3661, the precision of some calculations that affect the presentation of geometries on the map can be greatly improved when EPSG:3857 projection is used instead of turf. We can consider exposing the calculation utils here.