Allow parser to work with multiple types of data models

As discussed in the recent past, the Parser shall be able to use multiple types of datamodels, not just the one developed at IEK-10

Expected Behavior

When instancing the parser the user is able to define a DataModel class that should be used by the parser! The parser itself should just be a kind of API, unifying the different datamodels.

Current Behavior

Does just work with one type of datamodel

Possible Implementation

Define a abstract base class for datamodels which the user can choose from. When the JsonSchemaParser instance in created, one of the datamodels is selected (either Enum or with the class directly). It is necessary to move some of the current parser functionality into the datamodel as it is highly specific to the IEK-10. The ABC must define a set of standard functions each datamodel has to implement.