prototype ConservativeRegridding with FV approximation

[juliasloan25]

Closes #2398

Content

To Do

• We encountered zero area polygons when using spaces with odd h_elem, but not even h_elem. We should investigate this more

Prototype regridding latitude

Source field

Source field with one value per element

Destination field (remapped)

• Code follows the style guidelines OR N/A.
• Unit tests are included OR N/A.
• Code is exercised in an integration test OR N/A.
• Documentation has been added/updated OR N/A.

[ph-kev]

Thanks to @imreddyTeja for helping with debuging the zero area polygons. The zero area polygons are line segments on a lonlat grid. If you convert to Cartesian coordinates, and plot them on a XYZ grid, then the vertices of the elements have positive area. In particular, they correspond to polygons at the north and south poles.

See the plot below where the yellow nodes correspond to one of the zero area polygons.