global `all_existing_models` doesn't exist anymore in simgrid
This https://github.com/simgrid/simgrid/commit/e22da6010c6499813ff88c76041cf499ffbf2b67 cleans the use of globals in simgrid. But currently there's no way to get the list of models (all or by types) in the simgrid API.
I've a local fix for that btw.