EllipsoidGeodesic should have a fromStartHeadingDistance like EllipsoidRhumbLine

I asked [on the forum](https://community.cesium.com/t/move-a-cartographic-by-a-distance-in-meters/10234) about a function to "move" a Cartographic by a (meter) distance in a (heading) direction. I got a nice approximation using spherical equations that will be fine for my purposes, but it occurred to me that if I'm trying to do it, somebody else probably is too, and they might not be OK with the error. So, I'm opening this issue to request that somebody with better trig skills than mine implement a *correct* version of this method.

Start by locating the EllipsoidGeodesic and EllipsoidRhumbLine implementations and compare the existing fromStartHeadingDistance API on the rhumb-line class. Determine the geodesic method's expected inputs and outputs, then establish how correctness should be validated for moving a Cartographic by a heading and meter distance.

Written by the indexing model from the issue text.