Add option to output data in different vocabularies

[rubensworks]

For testing the performance of schema alignment at query time, we should add the ability to make different pods generate data using different vocabularies, and perhaps even emit different variants of the same query using different vocabularies.

[constraintAutomaton]

For my research, I’ve developed a prototype capable of generating multiple vocabularies. It’s not production-ready, but it is functional. Anyone interested in integrating it with SolidBench could use it as a reference or inspiration.

You can find the prototype here:
https://github.com/constraintAutomaton/rdf-dataset-fragmenter.js/tree/feature/multiple-vocab