- only throw runtime exceptions on all client calls
- wrap all internal exceptions to 4 defined exceptions the user has to deal with

fix: event order by natural event enum order, fixes issue with non-stable event ordering in zustelldienst

* load schema from specified path on initiation
* fixed and adjusted tests

* added loading of submission data schema
* added submission data validation to sender and subscriber flow
* added and adjusted tests and test data
* added attribute for skipping validations to config, fixed tests