GeoJSONs compatible with EU Information System

Splitting of from https://github.com/google/ground-platform/issues/2013:

Once GeoJSON download of job data is possible, next step would be to implement **columns** in the GeoJSON file that can automatically be read by the EU Information System for Due Diligence Reporting. [Requirements here](https://circabc.europa.eu/ui/group/34861680-e799-4d7c-bbad-da83c45da458/library/adebc1da-4e60-4479-83dd-ee344607c6f9/details?download=true).

The column titles need to be **precisely**:

- "ProducerCountry" (**mandatory** ISO2 country code) --> could be automatically calculated from the geometry or enquired in the survey with a dropdown menu country selection.
- "Area" (**mandatory** hectareage of the geometry) --> can be automatically calculated for polygons and enquired from the survey for point data. If not provided for point data, EU-Information will still ingest and default to 4 hectares for points.
- "ProducerName" (**optional**) --> to be enquired in the survey. Not mandatory, but best to be set as field in survey design already.
- "ProductionPlace" (**optional**) --> could be automatically calculated from the geometry based on global admin-datasets like GAUL, AND/OR enquired from the survey the same way as the producer name.

When the columns are provided and filled with data, the EU Information System will automatically ingest and fill the fields as shown below: