Integrate polish railroads

[RobusK]

Is your feature request related to a problem? Please describe.
Add integration for polish railroads, which also seem to be using hafas

Describe the solution you'd like
Polish stations and trains returning data ;-)

Describe alternatives you've considered
Portal Pasazera is reasonably useful, but I imagine more information can be had elsewhere

Additional context
Perhaps some of the endpoints used in this project could be of interest, since some of them deliver responses for german trains as well