ISIS Planetographic Projection Option bug

**ISIS version(s) affected**: 3.0+

**Description**
After some discussion with @dpmayerUSGS, it seems like some projections in ISIS that project assuming a spherical body should not be able to project to planetographic latitudes when equatorial radius and the polar radius are not equal.

For example if you look at the math for the sinusoidal projection in ISIS and compare it to the math found in [Map Projections-
A Working Manual](https://pubs.usgs.gov/pp/1395/report.pdf) by John Synder (where the sinusoidal information can be found on page 243), the math uses the model for a sphere. There is a model for an ellipsoid but ISIS doesn't support it.

As a result it seems like a user should not be able to define a planetographic latitude option for sinusoidal projection, especially if the equatorial radii and polar radii are different. Fundamentally, if your radii are the same you can specify either, but if they are different you also need to project assuming an ellipsoid rather than a sphere.

**How to reproduce**
There is no error to reproduce and ISIS accepts the planetographic option for sinusoidal maps, but your latitude will be off given any projection in ISIS that assumes a sphere. It will end up squishing your map based on the polar radii.

**Possible Solution**
Ideally, for projections that assume a sphere we should either update the radii on the mapping group or enforce the projections that assume as sphere use the planetocentric latitude rather than the planetographic latitude regardless of what the user requested.