[Code health] Harmonize geometry representation

Shapes are represented in remote db in features as point (GeoPoint), geoJson (string) and geometry (map). There’s also some confusion in the implementation about geometries vs LOIs. This design wasn’t intentional and we can improve it.

Ideas:

• Define generic geometry types independent of Ground model (perhaps import ~GeoTools?~ JTS)
• Instead of extending LocationOfInterest, have it contain an arbitrary Geometry
• Replace separate point, geoJson db format mirror GeoJSON where appropriate, but use Firebase GeoPoint for coordinates. Avoid nested arrays since they’re unsupported by Firebase.
• Load/save in local db (@scolsen)
• Update map to render new Geometry types (@jsunde)
• Delete old subclasses of LocationOfInterest (@scolsen)

[scolsen]

I think we can consider this one closed!

[JSunde]

I just merged the updates to the PolygonDrawingViewModel, #1279, to remove the MapPolygon and render a LineString for incomplete polygons and convert them to a LinearRing when they are completed.

I think that may have been the last of the rendering changes required.

Let me know if you think there is anything I missed! Otherwise I think we can probably close this issue.