Aas2openapi

Reworked a bug when submodels are requested that contain submodelElementCollections. Moreover, there have been some indications, that optional fields (or more specifically required fields) cause some issued with their default values. For now, there is no clear solution and further investigation and testing is needed.

From now on, it is not required to load environment variables for aas and submodel repository to start the middleware. Instead, some default values are used. However, it is still possible to set these environment variables before and they are used in the middleware. Use the .env.example-file as orientation for that.

Updated initial release