Implement Input Actor

[johanneshiry]

Create an actor based on the discussed design including an interface for different data sources.
This issues has to be addressed in conjunction with PSU#150

• design the OsmModel in the PowerSystemUtils repo
• hand in a PR for the new OsmModel
• design and implement an interface (trait) which provides an OsmModel in OsmGrid
• implement the basic filter for low voltage grid generation
• implement tests for everything