ARXML validation

[MLanghammer]

The ARXML files, we deal with, need to be validated against the Autosar XSD-schema.

Ideas:

• check for each franca to autosar integration test, whether the ARXML is valid
• add an (optional?) check to the command line tool that checks the ARXML after the transformation
• we can check the input ARXML files against the XSD schema as well to check whether our input is valid.