Built in method to move point North/South/West/East.

I have a few app in Cesium, and I constantly add to do some operation where I want to move a point in a direction. Usually North or East.

Now, It is already possible with some calculation like this [Sandcastle](https://sandcastle.cesium.com/#c=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)

What would be great to have, is a built in method on Cartesian (and/or) Carthographic where we could do something as simple as

Cesium.Cartesian3.North(position, distance);
Cesium.Cartesian3.East(position, distance);

position would be our starting position, and distance would be the number of meter we would like to move in that direction.

This would make those operation much more accessible I believe to people not user to geo calculation, and much shorter than having to calculate the normals etc... all the time

Start by reviewing the Cartesian3 and Cartographic APIs and the linked Sandcastle calculation. Determine how directional movement should be defined for North, South, East, and West, including the requested distance in meters. Done means the project has an agreed built-in API for these operations with behavior that can be validated.

Written by the indexing model from the issue text.