* refactors API geometry processing to use GeoJsonValidator and GeometryProcessor just like SimpleGeomForm
* moves cast_to_multipolygon, cast_to_rlp_srid, flatten_geom_to_2D, is_valid_4326 and is_area_valid into GeometryProcessor
* adds changeable SRID to GeoJsonValidator constructor
* updates test data
* updates test cases
* adds model and form mixin for PIK
* integrates mixins for compensation, ema and ecoaccount
* adds migration files
* extends API
* extends API test data
* adds is_xy fields to compensation, ema and ecoaccount reports
* adds is_pik information to detail views
* adds/updates translations
* adds creation tests with minimum data for intervention, compensation, ema and ecoaccount
* fixes bug where empty geometry would not be created properly using the API
* reworks key fetching from POST data, so inproperly stated keys will lead to an error for the API user, instead of silently working and use default data
* adds some logical checks for deductable_surface of eco account creation using api
* fixes bug that would have occured on creating compensations via api