Ensure mapping workflow works well for points (in addition to polygons)

[spwoodcock]

Is your feature request related to a problem? Please describe.

• Initially FMTM mapping was based on centroids.
• We switched to focus on polygons as it made more sense for census mapping and informal settlement enumeration (plus it's more intuitive for users).
• Certain use cases actually lend themselves to using points for the data collection: the MdP project in Brazil simply has POIs with free text input as the survey questions.

Describe the solution you'd like

• Ensure Entity creation works properly for points as well as polygons
• Allow for OSM data download as centroids (config option on frontend, pass through centroid:true to raw-data-api request)
• Ensure backend geojson handling all works for points
• Ensure points are displayed on project details page
• Ensure mapping status colours work for points on the frontend
• Ensure final output is as intended

[Sujanadh]

• point entities are created 👍
• splitting algorithm also needs to accept points as well
• most of the postgis function to parse geojson works for points as well unless unanticipated error

[spwoodcock]

I have successfully created projects for points, including point entities and point flatgeobuf file for the frontend.

All seems to be working for that part!

The key thing for this workflow now is centroid OSM extracts, checking the final output is as expected, and splitting algorithm (lower priority, as this is difficult).