earthobservations/wetterdienst: Add multiple storage pipelines, MOSMIX forecast and API

Add TTL-based persistent caching using dogpile.cache Add example/radolan.py and adjust documentation Export dataframe to different data sinks like SQLite, DuckDB, InfluxDB and CrateDB Query results with SQL, based on in-memory DuckDB Split get_nearby_stations into two functions, get_nearby_stations_by_number and get_nearby_stations_by_distance Add MOSMIX client and parser. Thanks, @jlewis91! Add basic HTTP AP