[ldd-cart] Make both attributes of Geographic class required

[wkiri]

Describe the issue identified (if applicable) The Geographic class contains only two attributes that are both optional. Therefore, it is possible to end up with an empty class.

Describe the solution you'd like Make both attributes (latitude_resolution and longitude_resolution) of the Geographic class required.

Describe alternatives you've considered N/A

LDD Dictionary Version 1.9.6.0

PDS4 IM Version 1.18.0.0

Need-by Date May 20, 2022 to be included in the next IM build.

Additional context DMSP workshop follow-up.

[thareUSGS]

updated latitude_resolution and longitude_resolution of the Geographic class to be required.

in v1960 (soon to main): https://github.com/pds-data-dictionaries/ldd-cart/blob/6d5212e9782d4c14ae87af9ccec29e32e7a4f43d/src/PDS4_CART_IngestLDD.xml#L2692

While this was also required by the FGDC metadata the CART namespace borrowed from, I always found it odd to support a "resolution" for vector data (points, lines, polygons). I updated their definitions to try to explain what this means for vector data (spacing between vertices in say a line or polygon). For rasters is more straightforward - simply the pixel spacing in degrees. Although a single resolution in degrees for latitude can also be confusing since on a sphere it shrinks as you go further north from the equator. But the key is that a derived map 2D product in "geographic" (lat/lon), really does need a single resolution (e.g., deg/pixel) for an image. For a global image, this would be the pixel spacing at the equator.