GlobeControls: Allow for more control over ortho camera near distance

[gkjohnson]

It's currently pulled out very far which means it always looks correct but can affect atmospheric rendering. See #859.

A solution would be to keep a certain "buffer" over the surface of the ellipsoid when positioning the near plane.

Screen.Recording.2024-12-09.at.3.17.14.PM.mov

[gkjohnson]

When computing the near plane for an orthographic camera it is just being set fairly crudely resulting in a large margin unnecessarily. Instead we should calculate the distance from the bottom (and top?) of the projection to an ellipsoid with some margin. The margin can then increase up to a certain point as the camera zooms out.