[FEATURE] Allow delegated generation of AAS and submodel

[tobijk2]

For a better integration of Basyx with exisiting systems where information is stored and accessible via external and proprietary services, AAS and submodels can be created by using an external service to instanciate the requested model element. For this a delegation for the instatiation would be helpful (as it was implemented for basyx v1).

This is especially helpful for providers with an immense amount of assets, where not all AAS and submodels for the assets can be instanciated.