Add get_world_info()

[Aidyn-A]

A method get_world_info() will be very useful for variety of purposes especially, for testing and debugging. Additionally, returning all zeros in get_rank_info() when parallel is not initialized can be misleading. I think it would be even better to have assert model_parallel_is_initialized() in future.

cc @eqy @crcrpar

[eqy]

I agree on the warning part, additionally we could perhaps format the output as a log and add it to debug logging in apex.

[Aidyn-A]

I agree on the warning part, additionally we could perhaps format the output as a log and add it to debug logging in apex.

I think the log is already present here. ~~I do not why it is not printing it though...~~ It prints the log when running with logging.getLogger("apex").setLevel(logging.INFO)