Use PPR routing by osm element type and id or level

[Robbendebiene]

The target and destination fields can additionally include the properties osm_type ("way" or "relation") and osm_id (int). We should try to use them or otherwise specify the level to assure that we calculate a path from and to the correct level. This is relevant to correctly export multi level train stations.

[Robbendebiene]

The osm_type/osm_id implementation is still incomplete and does not support nodes.

See also:

• Indoor Routing motis-project/ppr#35
• https://github.com/motis-project/ppr/blob/217585f424f6865693dd4aaa1a16f85daa574863/include/ppr/backend/request_parser.h#L72-L78