Investigate converting area backend to store GeoJSON

[ekes]

I've just realized how easy it is to make the backend store geojson instead of wkt. I've tested it with some of the files that were causing problems here ... and well it works (except somewhere on saving the entity it does assume it's some other format and makes an error message that's too large 😆 but the entity is saved by that point, and it works for display and other usage from there.

Originally posted by @ekes in localgovdrupal/localgov_directories#150 (comment)

[ekes]

Part of the issue https://www.drupal.org/project/geocoder/issues/3343202

Most simple solution to this is just put KML as the last processor.

[ekes]

Branch including a backend plugin: https://www.drupal.org/project/geo_entity/issues/3344441