Simplify project features response & prep for flatgeobuf osm extracts

[spwoodcock]

Issue

1. The response from get_project_features_geojson has many redundant keys, increasing the data transfer size when displaying the data extract.
2. We currently request for a data extract from raw-data-api, then download the resulting zipped geojson to /tmp, extract, and return the data. In the long run there is no need for this step. We can request a flatgeobuf file from raw-data-api, then either access directly from the S3 url (store the link in db), or upload the flatgeobuf to our own S3 for access.

Solution

1. Simplify the returned JSON response when getting data extracts, removing keys:

task_id
project_id
geometry.properties.label
geometry.properties.title
geometry.properties.version
geometry.properties.changeset
geometry.properties.timestamp

from each JSON object in the array.

2. Update to allow passing what format we require to raw-data-api & add comment TODOs about future changes.