switch API parameters to keyword arguments

This switches the input parameters for API calls to a generic
keyword argument catch-all which is then loaded into a dataclass
where the parameters are checked and forwarded to internal
function.

The dataclass gives more flexibility with the parameters and makes
it easier to reuse common parameters for the different API calls.

nominatim/api/__init__.py

@@ -23,7 +23,6 @@ from .types import (PlaceID as PlaceID,
                     Point as Point,
                     Bbox as Bbox,
                     GeometryFormat as GeometryFormat,
-                    LookupDetails as LookupDetails,
                     DataLayer as DataLayer)
 from .results import (SourceTable as SourceTable,
                       AddressLine as AddressLine,