Update Position validator to ensure reference can be specified alone

[cantrellb]

A position is allowed to be one of cartesian, cartographicDegrees, cartographicRadians or reference as given by the validator error statement. The validator does not check for reference only, its only checks against "cartesian*" values.

[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 99.66%. Comparing base (ea6b643) to head (83f614e).
Report is 6 commits behind head on main.

Additional details and impacted files

@@           Coverage Diff           @@
##             main      #54   +/-   ##
=======================================
  Coverage   99.65%   99.66%           
=======================================
  Files           9        9           
  Lines        1470     1477    +7     
=======================================
+ Hits         1465     1472    +7     
  Misses          5        5           

☔ View full report in Codecov by Sentry.
📢 Have feedback on the report? Share it here.

[Stoops-ML]

Thanks for this PR. I've never used reference before, but it seems that you're right.

I'd like this fix to apply to all classes that have a reference property, not just Position and ViewFrom. This includes references to things like rgba from another Color property and not just position.

The other classes are:

• Color
• EllipsoidRadii
• ArcType
• ShadowMode
• ClassificationType
• DistanceDisplayCondition
• BoxDimensions
• RectangleCoordinates
• EyeOffset
• HeightReference
• ColorBlendMode
• CornerType
• NearFarScalar
• Orientation
• Uri, not currently implemented. This class needs some work...

Note that a check is required to ensure that only one of the properties that can define a property is entered. For example, the Position class in this PR ensures that only one of cartesian, cartographicDegrees, cartographicRadians, cartesianVelocity, or reference is entered.

Moreover, let me know if you're planning on submitting more PRs in the near future. If so, I'll wait to release another version.

[Stoops-ML]

Merging this branch. Will finish the other properties in another PR