Add more fine grained control of tessellation of feature data

[jasonbeverage]

Recently I had to revert commit https://github.com/gwaldron/osgearth/commit/246ce0f14a71ea18b89d50e203cdd78b260b8e07 referenced in issue https://github.com/gwaldron/osgearth/issues/1779 to fix some issues caused by incorrect tessellation of large features.

The original intent of the commit was to allow more non-traditional feature data like a completely vertical polygon to render correctly. In hindsight this was an incorrect move as the gnomonic tessellation that is used in BuildGeometryFilter is just inherently incompatible with drawing a free form feature that isn't a 2.5D feature conforming to the earth.

There is probably some utility in being able to tell osgEarth how to tessellate the feature you're providing. This might just boil down to a boolean as to whether to treat the coordinates as raw coordinates on a mesh or as geographic feature data.