Create AASX reading/writing tutorial
This PR adds a tutorial script to the examples module, demonstrating how to use the aas.adapter.aasx module for reading and writing AASX package files.
The tutorial is based on the current master / 0.2.x branch, i.e. it uses the old AASXWriter interface, corresponding to DotAAS up to version 2.0.1. It needs to be adapted to the new interface, introduced by !69 (merged). This should probably be done in !69 (merged).
Fixes #69 (closed) (for now).