Discuss how to handle OSC1 engine dependencies

With the new generated engine approach also a .gitmodules file was introduced: https://gitlab.eclipse.org/eclipse/simopenpass/openscenario1_engine/-/blob/main/.gitmodules

This was not present in the "existing_open_scenario_1_engine" branch. We need to discuss how we want to handle the dependencies, since now in our environment:

• we have scenario_api twice as submodule (since also the environment depends on it).
• Same for units, since most of the other code depends on it. (even also MantleAPI)
• We would also not need the openscenario_api dependency, since we also have a precompiled library in a parallel folder.